>> The latest in additive manufacturing techniques see p66

November 2020 • Vol 30 No 11 • www.racecar-engineering.com • UK £5.95 • US $14.50 triple crown ’s TS050 seals outright win again

SPECIAL REPORT

PEUGEOT RETURNS! Tech update on the 2022 title challenger

HYPERCAR FUTURE Lifting the lid on the next generation of regulations

FORCE FIELD Revealing the science behind balancing performance

01 REV30N11_Cover_Le Mans_acbsBSMP2BSAC.indd 1 23/09/2020 11:34 THE EVOLUTION IN FLUID HORSEPOWER ™

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Untitled-3 1 05/05/2020 09:09 CONTENTS – NOVEMBER 2020 – Volume 30 Number 11

COVER STORY TECHNICAL 8 Le Mans report 48 The Consultant Toyota and Tuning leaf springs succeed where fails 50 Optimum G Suspended mass natural COLUMNS frequency numbers 5 Leena Gade 54 Graphene nanofluids High compression racing The miracle material 7 Mike Blanchet in suspension Rising stars and hidden delights 66 Additive manufacturing The latest developments FEATURES in printing technology 74 Danny Nowlan 16 LMDh regulations Why knowledge comes The start of a framework before questions for the new top tier class 81 Chris Aylett 24 Hypercar Full steam ahead? How the French manufacturer is forming its LMH contender 82 Bump stop 30 Balance of Performance The physics behind the decisions of parity 40 Interscope IP-1 Competing in the Silver category for young drivers, Porsche’s unraced IndyCar Steven Palette and Simon Gachet won the GT World Challenge Europe Sprint race at Magny Cours in the Sainteloc the week before Le Mans. Not bad preparation for the Spa 24 Hours in October

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Untitled-7 1 23/09/2020 19:59 ARP_Racecar_2020-10_v05_final.indd 1 8/24/20 11:19 PM THE ASPHALT STORIES – LEENA GADE

Prep school

How condensed schedules are putting added pressure on teams

arlier this year I wrote a column on how slightly damaged end plate. Things like that tests on track, and in dyno tests in a workshop, IMSA had put restrictions on the number all need to be checked and re-jigged, and it all then there will inevitably be questions when Eof personnel allowed at the track this takes time. With aero parts you have to be so something unexpected happens in a race. Why year due to the pandemic. Limited to 15 team precise in how you build them so there is no did that occur? Was material tolerancing out? members per car, we had gone into Daytona difference, part-to-part, when you put them Was the fitment incorrect? Was there incorrect not knowing anything different as that was all onto the car. And no difference car to car. strain on different fixations? we had anyway. We hadn’t had to reduce our If you have different people setting up numbers because we already run a lean team, so bodywork there is always something that can go Prototype parts were able to make the best of it and performed wrong. Is a bolt head flush with the bodywork? In Prototype racing, you are working with a pretty well. But if you are used to having 30 Is the angle of the carbon part that attaches to small number of parts that have been made people per car it’s more of a challenge. You have the floor at exactly the same angle between specifically for one function. These are not mass to think about which jobs to cut out, or work out both ? There are lots of differences, so we produced parts. As such, there will always be who can do two jobs, and what they should be. have jigs, tolerances that have been set and small differences that can cause small issues We are now allowed a team of 35 people, drawings to say how everything needs to be put which, in the case of the no.7 Toyota at Le Mans, but that’s the full team. We are a few races in together, but still someone needs to do it. cost the car the win. Again. and this is when it gets hard. The As a side note to that, a same people have been working performance engineer at Audi on the cars between events I was talking to said the fastest as we have had to run a lean car never wins at Le Mans. Bear ship back at base because of all in mind there is fastest lap, and the travel restrictions. Because fastest average. At each Le Mans, racecars require a lot of attention it is almost written into the to detail, that small team has to rules that if you have the fastest work incredibly hard. Now, when averages, the chances of your car we get back to the shop after an finishing on the top step of the event, the same team that has just podium are so tiny it is ridiculous. worked the race has to strip back The condensed schedule puts the car to analyse everything from even greater pressure on teams

a lifing perspective. Michael L. Levitt than were already there. The You also have to fine tune Racecars are like young children, unpredictable and require a lot of looking after schedules IMSA has created over everything because the cars the last few events have tried to take a battering at the racetrack. Bodywork is We spend a huge amount of time refining all minimise the time crews are at the track and, damaged from stone chips, contact or kerbs and of those little details to make sure the cars are where possible, fit everything in, from unload it all needs to be fixed before the next race. even from race to race. But then the no.77 car in to race, in just two days. That’s a tough call for Atlanta decided to put oil all over itself, the pit the teams running Prototypes as you need Three in a row lane, the track and the paddock. It was a massive time to prep the cars between sessions. There During the run of three races in June, we just oil leak. We had to do a lot of investigative work is never enough time when you have a full, had to get it done. We would come in on the to find out what happened, and why. It was a regular crew at the track and back at base, but Monday morning after the race event and work rare occurrence, not one we had experienced when you have reduced numbers it becomes flat out until the following Saturday, when we before, but that happens a lot on racecars. harder still. Factor in the travel schedule to and went racing again. We had a number of things from races and you start to realise the intense pre-prepped, in terms of gears and ratios and Expect the unexpected pressure on teams the Covid pandemic has so on, and we had assistance from Xtrac on that Wherever you go, be it a 2h40m race or a 24- brought in all forms of racing. front so at least that was pretty straightforward. hour race, or anything in between, there will With four races to go, this is the time we However, after those three races the cars always be something new come up that you really have to dig in. It’s going to be a hard had covered quite a few miles. And then we haven’t seen before. That’s just the nature of championship fight that tests us all to our went straight to for a six-hour race, racing. You find things you least expected. limits but that is the nature of racing! and came back with a lot of work to do! A good example of this is Toyota at Le Again, we had to go through the bodywork. Mans this year. Think how long that car has Leena Gade is the vehicle dynamics centre Things move in race situations and, if your wing been going for, how much testing that team manager and race engineer at Multimatic angle has changed, then maybe you have a has done. If they didn’t find it in two durability Engineering, UK You have to think about which jobs to cut out, or work out who can do two jobs, and what they should be

NOVEMBER 2020 www.racecar-engineering.com 5

05 REV30N11 Gade-MP2ACBSAC2.indd 5 23/09/2020 13:58 Design & manufacture of an adaptable range of set up, pit equipment & ight cases.

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VMEP FP HMRN July 2020.indd 2 15/06/2020 14:25 SIDETRACK – MIKE BLANCHET

Beauty in the beast Aesthetics aside, are F2 and F3 drivers being set a bad example?

ime was, for those who appreciate form engines with almost 60 per cent more power, like levels of talent and professionalism (with some that follows function, creativity and, many in motor racing I railed against it. The new, notable exceptions!) displayed by the seemingly Tyes, even sculpture, racing engines rather dumpy, one-make cars have little to very young drivers in F3 and F2. In particular, were objects of beauty. Even inanimate, differentiate them from their F2 cousins, certainly the skill they demonstrate in wheel-to-wheel without the adrenaline fix of their sound and for those less knowledgeable in such things. racing, often resembling 1600 in its fury, they could make one pause a breath or In contrast, the previous Dallara designs, heyday, just going a lot faster. two with wonder and nod with appreciation culminating in the F2018, were little beauties. One must understand, of course, that with at their concept and fine engineering. Almost delicate in appearance and construction, the majority of them coming from privileged Gleaming cam covers with multiple inlet together with the distinctive, bomb-shaped backgrounds, or with supportive families making trumpets standing proud between them, superb airbox, made them instantly recognisable. great sacrifices, these youngsters are well castings and forgings, purposeful-looking By inevitably being more expensive to buy educated and have been immersed in racing superchargers, even machine-turned and run, I feared for the future of F3. The fact culture since they were six or seven years of age. blocks – all stand out as examples of manual that, even in this pandemic-stricken world, near Many have known nothing other than competing rather than digital manufacturing skills. Think of 30 cars have been able to regularly fill the grid in karts and cars all through their upbringing. pre-WWII Alfa Romeos, Bugattis and Mercedes- maybe proves me wrong about old vs new F3. Benz engines. Post-war, a racing straight six, But where does all that money come from? Playing the fool be it from Jaguar, Aston Martin or Maserati, Perhaps, in some instances, better not to ask! In contrast, F1 drivers and their engineers / still today encourages a bystander to take Full credit, nonetheless, to Red Bull, , strategists make fools of themselves by being time and study it. The 1.5-litre Coventry Climax and others for their junior driver so obsessed with getting a slipstream tow in and BRM V8s of the 1960s were little jewels. schemes, which have a major bearing on F3 and qualifying at fast circuits that they trip over Compactness was a highlight of ’s F2 drivers and teams being on such healthy grids. each other and end up slower than if they’d just DFV, leading eventually to the gone for a non-obstructed flying lap, amazingly light but powerful picking up a tow as the opportunity pre-hybrid V10 F1 units, all as presents. So F2 and F3 drivers, in turn, pleasing to the eye as the ear. have done the same. The advantage gained from slipstreaming is real, but Piled on top rarely works as planned. This farcical So often now, however, particularly bunched-up weaving, apart from its with the increased adoption of hybrid potential dangers, impedes those power in Le Mans Prototypes and F1, drivers behind attempting to set a it’s difficult to even see the engines. All quick lap time. Consequently, culprits the paraphernalia of plumbing, wiring, should immediately be punished by a monitoring and control devices, not to grid drop – the regulation exists to do mention turbos and exhausts and all this, so why isn’t it implemented? Do their associated heat shielding, is piled we have to wait for someone to get on top, for aero reasons. badly hurt before action is taken?

Even out of the car, if fully XPB Also beyond my understanding dressed, the impression given is 19-year-old Australian driver, , won the 2020 F3 title at Mugello is the lack of consistency in setting that the engines are merely another and is one of the rising crop of talented individuals to come through the ranks track limits. I could barely believe component. A force-fed pump when the only limit set at Mugello was activated by internal combustion. Of course, Something else has impressed me of late. the gravel. The argument that it doesn’t matter that’s what engines, racing or otherwise, have When F1 live TV was free-to-air, I held out about limits as long as no advantage is gained is always been, but never before have they seemed against Sky. With so much other racing available, completely wrong. At all corners at every circuit to play such a subservient visual role. I reckoned I’d spend too much time watching the limit should be the same. Given the high- Inevitable really, given the progress of the HD screen that now fills a good part of our downforce cornering speeds of contemporary technology, but a bit of a shame. At least, lounge. But when live coverage became pay- racecars, which exaggerate even a small driving thankfully, they remain more interesting to look to-view only, I had to relent and sign up. Well, of error, probably the best compromise is the rule at than an and battery. course, I was right. I do spend too much time now used at Monza this year whereby at least two Aesthetics aside, when F3 departed from the watching F3, F2 and IndyCar, as well as F1, often wheels must remain on the track, as defined by decades-long concept of 2.0-litre, atmospheric including practice and qualifying. It’s become the white line, at all times. engines in small, lightweight to the compulsive and, I admit, is a bit sad. However, If the occupants of the cockpits cannot current breed of heavier racers with 3.4-litre what I have gained is an appreciation of the adhere to this, they really shouldn’t be there.

Never before have [engines] seemed to play such a subservient visual role

NOVEMBER 2020 www.racecar-engineering.com 7

07 REV30N11 Blanchet-MPAC.indd 7 22/09/2020 16:11 LE MANS 2020 – RACE REPORT Gold standard Toyota took its third win at Le Mans, but not without drama, while United Autosport triumphed in LMP2 and Aston Martin in the GTE Pro and Am classes By ANDREW COTTON

08-14 REV30N11 Le Mans report-MP2BSAC.indd 8 22/09/2020 16:15 he 2020 edition of the Le Mans In the LMP2 category, United Autosport Technology table with which it could attempt 24 Hours was never going to be won a dramatic and fiercely fought race to balance the different concepts. a classic, despite the best efforts between two chassis, Gibson- This table received a tweak in the run up Tof those trying to equalise the powered cars, one on Goodyear tyres, the to the race, but the upshot was the performance. Ultimately, Toyota finished up winner on . Strategy, speed and the raced with more weight than last year, up by winning the race as expected, five laps ahead ability of the third driver was key to the result 7kg, but were able to carry 0.1kg more fuel of the Rebellion, as also expected, but what in the second-tier class. to compensate. By contrast, the non-hybrids was unusual was the winning car spent 10 Aston Martin celebrated a double win raced at the same weight as in 2019 but were minutes longer on pit road due to a brake in the GT categories, winning both the Pro able to carry an extra 4.7kg of fuel, which duct issue that lost two laps, and the third- and Am classes with its Vantage models. The meant they could do the same number of placed Toyota had a long stop to change the victory in the Pro class came after extensive laps per stint as the Toyotas. exhaust manifold and turbo. testing in Aragon to ensure the Alcon brakes Lap times were also comparable in race Those events should have put them were able to go the full distance without trim and indeed, the Rebellion put in the within reach of the Rebellion that, for much change. The other contenders did change at fastest lap of the race, a 3m19.264s set by of the race, had a trouble-free run. Other than least the fronts, but further work on aero and early on. Happy hour at dawn, a slightly longer stop to change the nose set-up meant the Aston’s rear tyres would also when the air temperature is low and the track on Sunday, the ORECA-chassis entered by last a full double stint, unlike 2019. has rubbered in, didn’t bring the usual fast lap the watch maker made it through the race runs as by then the race was almost settled. without fault to record a memorable podium n LMP1 Toyota went into the race having qualified at what was the last Le Mans for the team. Although the rest of the World Endurance first and third, Senna lining up on the front The ByKolles had another ignominious Championship was governed by a Balance row alongside Conway. While the Rebellions race that ended with a crash on Saturday of Performance system, the restrictions were could match the Toyotas over a single lap, night, Bruno Spengler spinning at Dunlop lifted at Le Mans with the two cars from the they were not able to live with them in traffic. Curves. But although the car has been same team starting with the same weight The hybrids’ push-to-pass power delivery developed in-house, it was a long way off and fuel allowance as each other. The ACO system meant they could dispatch the slower the pace from the start. and FIA therefore only had the Equivalence of cars more effectively than the non-hybrids.

TECH SPEC: Toyota TS050

Chassis: Carbon monocque Suspension: Double wishbone and torsion bar Dampers: Öhlins four-way Brakes: Brembo discs, Akebono pads Tyres: Michelin Wheels: Rays Lights: Laser Fuelling valve: Staubli, Krontec Dimension: 4650 x 1900 x 1050mm Weight: 888kg Engine: 2.4-litre, bi-turbo hybrid, 90 degree aluminium block Turbos: Garrett Oil: Mobil Clutch: ZF-Sachs Gearbox: Xtrac The no.7 Toyota took and the team admitted it was running out of words to say to its drivers and crew after the win was denied them for a third successive time

NOVEMBER 2020 www.racecar-engineering.com 9

08-14 REV30N11 Le Mans report-MP2BSAC.indd 9 22/09/2020 16:15 LE MANS 2020 – RACE REPORT

On pace alone, the no.7 Toyota led, and The team replaced the whole system, n the lead extended dramatically in the first including a turbo, and the repair lasted 29 LMP2 hour as it hit a slow zone on the front straight minutes. That was the end of their challenge If there was ever to be a more competitive once, the no.1 Rebellion twice, losing more for the overall win, but there was still a class than LMP2, it is hard to imagine. The than 40 seconds in the process. In the past, podium place on offer. The two Rebellions class featured strong teams from Europe, the with multiple contenders for overall victory, ran second and third at this point, but the US and Asia, and platinum drivers alongside race director, Eduardo Freitas, has focused Toyota had almost 12 hours to make up the golds and silvers that were not slow. on the LMP1 cars to ensure something like necessary lap to snatch third. The cars have been raced for years and that doesn’t happen, while the other classes That went wrong when Conway ran over are proven and extremely reliable. All entries have been ignored in that respect. This year, debris on the track, damaging the underfloor were fitted with Gibson’s 4.2-litre GK428 V8 though, it was done on track condition alone. aerodynamics and costing lap time (see the engine, the and ran with The no.7 car was, for the third year in rising averages chart below). However, they Xtrac gearboxes, while the was fitted a row, the faster of the two Toyotas. Mike were helped in their quest for the podium with Hewland’s TLS200 unit. Conway, and Jose Maria when the clutch on the no.3 Rebellion failed. On paper the grid looked strong, and Lopez once again set their car up perfectly for While was able to drive discounting the cars that featured bronze the conditions and, when they established a around the problem, it caught out Deletraz, drivers there were more than 15 cars that lead of more than a lap on Saturday after their who ran wide at the Indianapolis corner and could have challenged for the win (Dwight team mates hit trouble, they dared to dream tagged a barrier, requiring a stop for repairs. Merriman crashed his IDEC ORECA in practice this could have been their year. That settled the race for the podium. and was replaced by after The no.8 Toyota of , Toyota’s no.7 crew stood on the third step being diagnosed unfit to race due to back and Sebastian Buemi ran behind the no.1 Rebellion team, with the problems). With short stints of around 30 third in the opening stages, but early in the no.8 car crew victorious for the third time. minutes, and with seven teams all lined up second stint Buemi pitted with a left rear Once again, it was pure luck they made it, next to each other in the pit lane, cars pitting puncture that threw the car out of the regular this time with Hartley who won in 2017 for out of sequence meant there was a lot of time sequence. The sister car, meanwhile, Porsche and 2020 for Toyota. when LMP2 cars were on pit road. metronomically put in 11-lap stints that were fast and consistent, and when the no.8 car suffered overheating brakes due to debris in the brake ducts, they knew they would need a long stop to repair the damage, or risk not making it to the end of the race. They did so on during hour seven and dropped off the lead lap altogether. In fact, they lost two laps. Their pace was consistently slower than the no.7 car, despite the drivers of that one staying off the kerbs, protecting the car and preparing for a potential fight on Sunday morning to hold their track position. The race then settled into its natural rhythm, with the three top cars circulating together. The no.3 Rebellion had lost time with a burnt rear bodywork that needed changing, and then Louis Deletraz hit a suicidal rabbit during the night that broke the nose and splitter of the car. At 2.40am, the race turned when the no.7 The no.7 Toyota was again the faster of the two TS050s, setting pole position and leading through the early hours before a car stopped with a holed exhaust manifold. mechanical failure again denied the team its dream result

Rising Average Lap Times - LMP1 220

215

210

205 Lap Times in seconds 200

195 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Laps

8 - Toyota 7 - Toyota 4 - ENSO 1 - Rebellion 3 - Rebellion

10 www.racecar-engineering.com NOVEMBER 2020

08-14 REV30N11 Le Mans report-MP2BSAC.indd 10 22/09/2020 16:15 Blocked fuel filters from contaminated Hanson had taken over the United car If ever there was to be fuel was thought to be an issue for some of with over an hour of the race remaining, after the cars, but key to the race was the length Di Resta’s puncture curtailed his last stint a more competitive of time the cars spent refuelling. United to nine laps, rather than the expected 10. Autosport spent more than five minutes The Jota car pitted as scheduled and United class than LMP2 it is longer on pit road than the no.38 Jota entry, believed they would not need an extra stop. against which it battled for the class win However, with 55 minutes remaining, an hard to imagine (52m50s compared to 47m30s, although AM car crashed at Tertre Rouge, necessitating being held in pit lane under a slow zone be implemented there. This conditions can affect the total pit time). Time enabled some fuel saving at both Jota lost in the pit had to be made up on track and United. No sooner had the mess been with clever use of safety cars and slow zones. cleared up, though, there was another There were a number of technical issues Ultimately, the battle was settled in favour incident at the Porsche Curves, where the early on. One Signatech Alpine suffered a of the United car, which recovered from a Graff LMP2 car crashed. For this, a full safety water leak as early as the first lap, while the puncture that cut ’s last stint in car was used, allowing more fuel saving still. the Racing for Holland ORECA also had a the car two laps short and forced the team Hanson managed to conserve enough to water leak. One of the United cars had an oil to splash for fuel towards the end of the get 12 laps out of his stint, so when the SC leak having run at the front of the pack, and race. The car’s responsibility fell to di Resta’s was withdrawn after 15 minutes, Hanson Dragonspeed blamed engine supplier Gibson co-driver Phil Hanson to fend off Anthony continued for another four laps before pitting. for its retirement from the race. However, Davidson in the Jota entry and it was nip and Next door at Jota, the team was hoping Gibson responded that it potentially had only tuck all the way. Jean-Eric Vergne suffered that Davidson would be able to save enough one problem with one engine, which was one a suspension failure in the final hour which fuel to remove the need for a final stop of the Dragonspeed cars, but that it retired took them out of contention, and a crash altogether but, for some reason, the Briton with a suspension issue before Gibson’s for James Allen in the final hour cost Graff a only managed to get 11 laps out of his car. His engineers could get to the bottom of it. podium, but also brought out the safety car. subsequent pit stop was shorter than that of Hanson – one lap less of fuel required – but that only made five seconds difference. With the gap at the flag just over half a minute, it simply wasn’t enough to make up the deficit. While Hanson stood up to the pressure admirably in the final stint, earlier in the race, it was the pace of Di Resta and Felipe Albuquerque on Sunday morning that really made the difference. Da Costa, taking over the Jota car on Roberto Gonzalez’s used tyres in a strategic gamble for the team, was slower than the United car, losing around 15s on the stint. Although Da Costa went quicker when he had new tyres, the second stint on the same set (he did a quadruple stint) was back in the 3m 33s bracket. Meanwhile Di Resta’s stint just after 10am was the fastest P2 stint in the race, a good half-second quicker than Da Rebellion took second place after a pretty much trouble-free run, but the team was still five laps behind the winning Toyota Costa to put United in commanding position.

LMP2 Gap Graph to #22 - 1200 1100 1000 900 800 700 600 500 400 300 200

Gap to #22 in seconds 100 0 -100 -200 -300

-400 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Laps

22 - United 38 - JOTA 26 - G-Drive 31 - Panis 36 - Alpine 37 - JCDC 28 - IDEC 32 - United

NOVEMBER 2020 www.racecar-engineering.com 11

08-14 REV30N11 Le Mans report-MP2BSACBS.indd 11 23/09/2020 11:11 LE MANS 2020 – RACE REPORT

TECH SPEC: ORECA LMP2 winner

Chassis: Carbon monocque with Zylon panels Suspension: Double wishbone and torsion bar Dampers: PKM Brakes: Brembo discs, Brembo pads Electric power steering: Kayaba Tyres: Michelin Wheels: OZ Lights: Osram Fuelling valve: Staubli, Krontec Dimension: 4745 x 1895 x 1045mm Weight: 930kg Engine: Gibson 4.2-litre, normally-aspirated, 90-degree V8 GK428 Injectors: Cosworth Oil: Motul Clutch: Tilton United Autosport took the win in LMP2, despite losing four minutes on pit road. The margin of victory at the Gearbox: Xtrac chequered flag was just over half a minute after a dramatic final hour that saw crashes and ultimate racecraft n GTE

With just eight cars in the ‘Pro’ class this was not going to be one of the classic races, although 22 cars in the ‘Am’ category was interesting. The automated BoP system does not apply to Le Mans where human decisions take priority. Porsche subsequently felt it was on the receiving end of that issue and the rising averages certainly shows the new 911 RSR (introduced last year, but debuting at Le Mans) as the slowest of the GTE-Pro cars. For much of the race, the no.97 Aston Martin had the speed advantage compared to the no.51 Ferrari that finished second, just 93 seconds behind after 24 hours of racing. The difference between the two cars was that the Ferrari changed the front brakes during the race, the Aston Martin did not. Although the drivers did not necessarily focus Porsche sat on pole position but, in the race, the other cars showed their true potential, leaving the Stuttgart marque behind

GTE Pro performance Position No. Team Car Drivers Laps Best Average S1 - Best S2 - Best S3 - Best Porsche - Best Ford - Best Top Speed 1 97 Aston Martin Vantage AMR Martin/Lynn/Tincknell 346 03:50.321 03:51.740 35.702 88.012 105.910 17.726 6.537 306 2 51 AF Corse Ferrari 488 GTE Evo Calado/Peir Guidi/Serra 346 03:51.002 03:52.014 36.393 88.268 106.131 17.722 6.603 304 3 95 Aston Martin Racing Aston Martin Vantage AMR Sorensen/Thiim/Westbrook 343 03:51.277 03:52.864 36.426 88.462 106.246 17.801 6.716 303 4 71 AF Corse Ferrari 488 GTE Evo Rigon/Bird/Molina 340 03:52.059 03:52.730 36.434 88.522 106.422 18.025 6.673 305 5 82 Ferrari 488 GTE Evo Pla/Bourdais/Gounon 339 03:51.408 03:52.667 36.310 88.292 106.280 18.004 6.630 306 6 91 Porsche GT Team Porsche 911 RSR - 19 Lietz/Makowiecki/Bruni 335 03:52.695 03:53.809 36.099 89.165 106.514 17.656 6.591 299 7 92 Porsche GT Team Porsche 911 RSR - 19 Christensen/Estre/Vanthoor 331 03:52.136 03:53.267 36.345 89.025 106.282 17.608 6.502 300 8 63 WeatherTech Racing Ferrari 488 GTE Evo MacNeil/Vilander/Segal 185 03:52.056 03:53.845 36.610 88.769 106.473 18.150 6.654 302

Rising Average Lap Times - GTE Pro 236

235

234

233

232 Lap Times in seconds

231

230 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 Laps 97 - Aston 95 - Aston 92 - Porsche 91 - Porsche 71 - Ferrari 51 - Ferrari

12 www.racecar-engineering.com NOVEMBER 2020

08-14 REV30N11 Le Mans report-MP2BSAC.indd 12 22/09/2020 16:15 DESIGNING A LE MANS WINNER? WE HAVE THE DAMPERS YOU NEED!

CONGRATULATIONS TO ASTON MARTIN RACING FOR WINNING THE GTE PRO CLASS AT THE 24H OF LE MANS 2020 AND THE FIA WORLD ENDURANCE CHAMPIONSHIP (WEC) MANUFACTURERS’ TITLE

TO TF SPORT FOR WINNING THE GTE AM CLASS AT THE 24H OF LE MANS 2020

Öhlins Racing has been an integrated part of the industry as well as the motorcycle and for 40 years. Our philosophy has always been to supply the aftermarket, OEM partners and teams with high-end suspension technology, and we are all dedicated to exceeding our customer’s expectations throughout the world. Our passion for innovations and state-of-the-art technology motivates us to search for the next generation of advanced suspension technology. For more information visit www.ohlins.com or follow us in our social channels.

ÖHLINS RACING AB • Instrumentvägen 8-10 s-194 51 Upplands Väsby Sweden • +46 8 590 025 00 • [email protected]

ohlins_lemans24_astonmartin_210x297mm.indd 2 2020-09-23 14:35:15 LE MANS 2020 – RACE REPORT

TECH SPEC: Aston Martin winner GTE-Am

Chassis: Production-based aluminium Suspension: Double wishbone and torsion bar Dampers: Öhlins Brakes: Alcon Electric power steering: Kayaba Tyres: Michelin Wheels: TWS Lights: Hella Fuelling valve: Staubli Weight: 1251kg Engine: AMG Mercedes 4.0-litre, bi-turbo, 90-degree V8 Injectors: Cosworth Turbos: Borg Warner Oil: Total Clutch: Alcon Gearbox: Xtrac Partner team, TF Sport, won the GTE-Am category after also benefitting from improved rear tyre wear this year

TECH SPEC: Aston Martin GTE Pro winner

Chassis: Production-based aluminium Suspension: Double wishbone and torsion bar Dampers: Öhlins Brakes: Alcon Electric power steering: Kayaba Tyres: Michelin Wheels: TWS Lights: Hella Fuelling valve: Staubli Weight: 1251kg Engine: AMG Mercedes 4.0-litre, bi-turbo, 90-degree V8 Injectors: Cosworth Turbos: Borg Warner Oil: Total Clutch: Alcon Gearbox: Xtrac Aston Martin spent three days perfecting its braking strategy in preparation for Le Mans, and it paid off as the team completed the race without changing the brakes to deliver the win for the Vantage

on saving the brakes from the start, they knew they would have to go the full distance Advance warning without a change and so were careful. According to Michelin, the key was their f the stewards decisions, number 108 provide false information and so there should ability to look after the rear tyres, and even in caught the eye. AF Corse’s Ferrari no.51 be no further action taken. the Am category that made a difference. What Owas investigated as the ignition advance ‘The only question remaining to the Stewards can be seen from the rising averages chart is did not match what was on the data sheet that is whether the ignition advance must strictly the no.97 Aston was comfortably faster than forms part of the homologation of the cars and is comply with the values set out in the Datasheet, the opposition, even with drivers paying close supplied by Ferrari to the FIA. which is gathered under specific conditions, not attention to brake wear. The sheet is used as part of the Balance of ambient conditions,’ read the judgement. Ferrari complained the BoP did not suit, Performance process, and the FIA and ACO use it ‘The Competitor argues that if their engine but in race conditions its cars were fast and to help determine lambda and pBoost settings. was tested under the conditions specified, the instead it was Porsche left embarrassed. The AF Corse argued that the team has certain control results would match the datasheet. There is no 911 sat on pole after the new hyperpole strategies that set performance under different evidence to the contrary. Further, the Stewards qualifying session, but blown fuses on the conditions to ensure reliability and that ignition are concerned that the data gathered does not power steering systems put both cars out of advance is one of these, and is therefore not part use a controlled sensor. Engine parameters are a contention. Even before that, though, they of the performance balancing act. complex multi-variable system. It is clear to the were well off the pace, and will no doubt Stewards that the datasheet must be accurate, want a review into their own performance No further action and that pBoost and Lambda are fixed by the and the organisation that regulates the BoP. The stewards were satisfied that, as the ignition Balance of Performance. However, it is not clear With only two cars from a planned four, it advance is measured using the teams’ own data that the other parameters of the engine can be was perhaps a blessing their commitment to and not an FIA sensor, there was no attempt to expected to be constant.’ the race reduced on this performance.

14 www.racecar-engineering.com NOVEMBER 2020

08-14 REV30N11 Le Mans report-MP2BSACBS.indd 14 23/09/2020 11:11 Congratulations RAYS

TOYOTA GAZOO Racing earned a third consecutive overall Le Mans 24 Hours win with the TS050 HYBRID after a turbulent and ultimately-successful race at the using RAYS Engineering wheels.

WWW.RAYSWHEELS.CO.UK 0121 661 63 63

Untitled-2 1 23/09/2020 11:19 LE MANS – HYPERCAR

Power games

16 www.racecar-engineering.com NOVEMBER 2020

16-22 REV30N11_Le Mans regs-MPAC.indd 16 23/09/2020 11:27 riday’s traditional ACO press four chassis manufacturers in this second- conference at the 2020 edition of the generation rule set. The gearbox will be saw the French available mid-2021 for hybrid system testing, The top class in Forganisation outline regulations and cars are expected on track later that year for Le Mans Daytona h (LMDh) and reveal in preparation for a race debut in 2022. partners for the project, including Xtrac for The P1359 gearbox developed for the endurance racing will the standard gearbox, Bosch for the hybrid class is a seven-speed transverse arrangement motor and Williams Advanced Engineering with an integrated motor-generator unit be called Hypercar (WAE) to provide the battery for the class that (MGU) driving into the gearbox through an will be part of a global Prototype platform. optimised gear train. The integration of the and will incorporate There are two ways of entering the top hybrid system is a vital attribute of the LMDh class that are already well documented. specification and Xtrac has worked closely both [LMDh and Either a manufacturer may build its own car, with the ACO, IMSA, Bosch and Williams including chassis, suspension, brakes, engine Advanced Engineering to ensure the package, LMH] concepts and, crucially for some, the hybrid system. Or function and overall operation is optimised a second option will allow a manufacturer for cost, weight, performance, and reliability. to buy an homologated chassis and fit its The LMDh spec hybrid system has a own engine and aero package (similar to relatively modest output of 30kW, which the process allowed in the US by the IMSA is hardly intense when one considers the organisation under its auxiliary exhaust gas MGU-H on the Porsche International (DPi) regulations) but fit a spec, 919 Hybrid that raced at Le Mans from low-powered hybrid system. 2014-2017 achieved the same contribution in charging the battery in wide-open throttle. Global reach WAE supplied ’s spec battery The initial intention was that Le Mans Hybrid for the all-electric series’ first four seasons, (LMH) cars run in the FIA’s World Endurance culminating in a system with a capacity of Championship, while the LMDh concept was 28kW that produced a nominal race output developed by American organisation IMSA. of 180kW. It is also delivering the battery pack However, manufacturers and governing for the Extreme E series, which will have an bodies want to balance the two concepts to output of 400kW, and will be the sole supplier allow them all to compete globally, increasing of it in Extreme E’s inaugural season. return on investment and controlling costs. Therefore, rather than differentiate Battery challenge between the LMH regulations the FIA and As for the LMDh spec battery system, Williams the ACO created, and the LMDh regulations Advanced Engineering notes the challenge (the h has never been officially identified), the is very different from the spec systems it top class in endurance racing will be called has provided in the past. Mainly because Hypercar and will incorporate both concepts. throughout the race at Le Mans, there is a This goes alongside announcements substantial delta in ambient temperature, air earlier this year that the four chassis pressure and humidity. manufacturers from LMP2, namely ORECA, The battery and its ancillaries will be Dallara, Ligier and Multimatic, would also homologated, so the spec must perform supply the chassis for the LMDh entry to the well in each environment regardless, and top class. These cars will be developed and understanding the working environment of homologated for five years, using the same the battery will play a significant role in the process as the current DPi cars that currently early part of its design phase. race in IMSA’s WeatherTech Sportscar series. Inside the battery, some elements are However, in order to protect its current critically separated by an air gap that forms competitors, IMSA has yet to commit to isolation between components, some of allowing LMH cars such as the Peugeot, which carry current. Should a loss of isolation Glickenhaus and Toyota to race in the States occur, new electrical pathways could form until the performance balancing process between parts, for which the amount of has been proven successful. That process is current and the length of time the current proving complicated, though, and the finer runs are not managed. details have not yet been finalised. As such, the spec system for the LMDh category will probably be conservative in There was some flesh Bespoke gearbox its volume to ensure there are no issues added to the bones of While Peugeot dominated the LMH concerning isolation. discussions, the first stage of the LMDh The WAE LMDh battery will likely use the LMDh regulations at announcements in was that Xtrac lithium-ion cell chemistry. The architecture will provide a bespoke gearbox for the new of the electrode stack in the cell dictates Le Mans, but the picture category that will house the Bosch hybrid the temperature range the cells can work system. The British company already provides efficiently in, so this will almost certainly differ is by no means final the gearbox to ORECA, Multimatic and Dallara from what WAE has used in its Formula E units By ANDREW COTTON LMP2 cars and was then chosen to supply all as they operate in a narrower window.

NOVEMBER 2020 www.racecar-engineering.com 17

16-22 REV30N11_Le Mans regs-MPACBSAC2.indd 17 23/09/2020 13:59 LE MANS – HYPERCAR

Diagrammatic of what has been released so far in the way of LMDh specifi cations

To date, WAE has characterised many gearchange system. It houses full ‘We have compelling diff erent cell chemistries and designed a form ground and Xtrem polished gears unique pack construction to enable the and shafts in a magnesium RZ5 casing, technology to help desired cell behaviour for the various race which is a structural part of the car taking series it supplies. all of the loads from the rear suspension make motorsport even Regarding capacity and performance as and rear impact structure, rear wing and far as rate of discharge, no information has safety wheel tethers. more relevant and been disclosed yet. However, as performance The gearbox has a maximum combined is primarily driven by how power is drawn internal combustion engine (ICE) and MGU from the cells within their operating power capability of 585kW (785bhp), with the exciting, which also temperature window, the mechanical engine speed operating within the range of installation will be critical, and it is not known 6000 to 10,000rpm. As each chassis builder infl uences the crucial yet whether that will be left to the teams or can homologate its own powertrain with be in the hands of Williams. specifi c gear ratios, the integrated MGU evolution of the next The mechanical installation, which drives through a novel gear train that will be includes the cooling package, infl uences the homologated for each engine. It ensures that generation of road cars’ output potential, but it’s a very narrow road no matter what the maximum engine revs, to performance development. As such, the the MGU is matched to the engine speed, Adrian Moore, chief executive at Xtrac primary infl uencer in motorsport battery ensuring no one engine gains an advantage, performance is the software that governs parity being the ethos behind the new class. how the energy is deployed and regenerated The gearbox also includes a limited-slip more relevant and exciting, which also – something WAE will likely lock for the teams plate diff erential with an externally gas infl uences the crucial evolution of the next running in LMDh. ‘The four appointed chassis charged pre-load and a semi-dry sump oil generation of road cars.’ suppliers, Dallara, Ligier, Multimatic and system. Integral to the gearbox is a 3.0-litre ORECA, provided invaluable feedback to Xtrac engine oil catch tank, which simplifi es the Complete package during the design of the ,’ says powertrain installation. The whole package, The three companies, Bosch, Xtrac and Xtrac’s chief executive, Adrian Moore. ‘That including the MGU drive, but not including Williams Advanced Engineering, worked ensured we met their requirements with a the MGU itself, weighs 78kg (172lb). together to present the organising common transmission that will fi t all chassis The P1359 gearbox, with its integrated bodies with a complete package. Bosch’s without modifi cation. It was a vital goal to hybrid system, is a critical new product for responsibilities include the e-machine, make sure we achieved the cost-eff ectiveness Xtrac. ‘We see the transition to electrifi ed inverter, vehicle control unit to the brake-by- of this new class of racecar.’ propulsion systems both on the road and wire system and other peripheral electronics, The P1359 gearbox uses Xtrac’s well- the track,’ says Moore. ‘We have compelling as well as key e-mobility hardware for the proven P1254 integrated valve actuator (IVA) technology to help make motorsport even LMDh programme. Additionally, Bosch

18 www.racecar-engineering.com NOVEMBER 2020

16-22 REV30N11_Le Mans regs-MPACBSAC2.indd 18 23/09/2020 14:00 provides an intelligent hybrid-power ACO and IMSA trust us with the responsibility ‘Bosch and Williams have a lot of management software that controls the of system integration in the future. For us, motorsport experience,’ says Simon Hodgson, distribution of torque between the ICE, this is the next step in demonstrating our vice president competition, IMSA. ‘This is e-machine and brake-by-wire system, based many years of expertise and competence in a bespoke unit that has been designed on driver demand. motorsport, both with our technology and and packaged with all the requirements ‘With the hybrid system and our with our system engineering expertise for a associated with LMDh. components, we are making an important perfect interaction of all components.’ ‘Working with companies that are fl exible contribution to the new racing category,’ As the rule set fell under the watch of and able to be constructive, it was apparent says Dr Klaus Böttcher, vice president, Bosch IMSA, it made the fi nal decision on suppliers, they would be partners. Xtrac was supplying Motorsport. ‘We are particularly proud that in association with the ACO. to three of the constructors already.

NOVEMBER 2020 www.racecar-engineering.com 19

16-22 REV30N11_Le Mans regs-MPAC.indd 19 23/09/2020 11:27 LE MANS – HYPERCAR

Toyota demonstrated this roadgoing version of its hypercar at Le Mans. It will start testing in race trim in October this year and will be raced in 2021

‘What we were trying to achieve with ‘Shifting to ByKolles and Glickenhaus, if LMDh was a common gear case for efficiency they are performing on time, it is a case of ‘Working with companies of cost. The collaboration meant we could how long it will take them to reach 95 per arrive at a common single class. We have cent. Then, on our side we will use a front that that are flexible and been working with the partners for some is totally new, and a brand new rear, but we time. It has been a very positive process.’ have never done a tyre that size. The first test able to be constructive, Focus on the LMDh regulations at Le Mans will be interesting because if nothing works it saw the basic outline of the car revealed, with could be the tyre or the car. it was apparent they weight set at 1030kg, a combined power ‘Regarding LMDh, if the technical data output from ICE and hybrid at 500kW and a shows it will be equivalent to ByKolles or would be partners’ point on the lift / drag graph at which both Glickenhaus, they can use the similar tyre but, Simon Hodgson, vice president LMDh and LMH cars will meet. is if they need a different type of tyre, we will 3150mm by regulation, there is a maximum be allowed to do it. Looking at the basic data, competition, IMSA length of 5100mm and width of 2000mm. they cannot wait for the car to exist before we The car is priced at €1m (approx. $1,171,040), do the tyre, so they have chosen the same. split between €300,000 (approx. $351,310) Chassis makers can then design their cars.’ For them, the hybrid is only activated over for the hybrid system and €700,000 (approx. 120km/h in the dry and power is likely to be $819,570) for the spine of the car. Parity of performance limited due to a small energy storage. They Having different tyre sizes will be something therefore need to build an ICE engine capable Tyre concepts that those sitting in the simulation working of producing 500kW and convert the torque Tyre sizes for the LMDh category were not group have to overcome to balance the cars from back to front over the set speed limit. identified and Michelin, the sole tyre supplier ahead of their introduction. They also have The basic concept for the LMH cars is that to the top category of both LMH and LMDh to find a way to balance power delivery. In they will be able to race at Le Mans at a lap concepts, explained how the two concepts order to achieve parity of power, limits were time of between 3m25s and 3m30s in the would have totally different requirements, set at 500kW, with the LMH cars producing first year. The LMDh cars should be able to do and therefore their own bespoke tyre sizes. 200kW of power on the front axle through the same lap time, particularly as they race ‘The Toyota tyres are the same size as their hybrid system, while the LMDh concept on the LMP2 platform that qualified at 3m24s today, but [on] the Glickenhaus you have a cars will produce 470kW from their internal at Le Mans in 2020. However, the LMDh fuel narrower front and wider rear,’ says Matthieu combustion engine, and a further 30kW from tank sizes are too small to compete on a level Bonardel, head of Michelin’s business line of the spec hybrid system. playing field with the LMH cars. the LMH tyres the company is developing. Power delivery for the LMDh cars will IMSA does not have a target lap time on ‘This is coming to life, they are not ready yet. be constant, with the low-power system any specific circuit, but do not want the LMDh Toyota are the first tyres ready and they will supporting the ICE throughout the cars to be too much quicker than the current test soon, and we have enough data and acceleration phase, but the LMH cars will not DPi cars as they will have to be integrated at confidence to be close to the target. have full hybrid power all the way round a lap. some point in the middle of the 2022 season.

20 www.racecar-engineering.com NOVEMBER 2020

16-22 REV30N11_Le Mans regs-MPAC.indd 20 23/09/2020 11:27 www.bredaracing.com or contact us at [email protected] www.bredaracing.comor contact us at [email protected] or contact us at [email protected] or contact us at [email protected]

Untitled-4 1 23/09/2020 14:47 LE MANS – HYPERCAR

‘This is the next evolution, the next step, Rubber necking

and will be around for a long time, bringing ichelin is sole tyre supplier for LMDh and LMH and plans to use the opportunity to introduce both stability and cost control’ Mnew technology into its range. ‘Today we have the technology to put a sealant in Simon Hodgson, IMSA the tyre, which makes it resistant to puncture,’ explains Michelin’s Matthieu Bonardel. ‘You put a gel in the tyre The organisation says it will increase or reduce ‘Today, the step forward is the same tech and that fills the puncture and keeps the pressure. We the hybrid power according to track when specification so that LMDh can compete in have that technology, but when you try to put 200g they start to see the LMDh cars. two championships around the world. There more weight into each tyre, so almost 1kg, it could cost ‘Technically, there is no reason why LMDh is more news to come. Today we also want to half a tenth, and then the driver says it is slower. What will not be in competition sometime in 2022,’ speak to our manufacturer partners.’ is the risk of the puncture? They then don’t want it. says Hodgson. ‘We are going to respect all Michelin was clear that the different tyre That started with Audi. We told them we could get rid entrants that are committed to us. LMDh is sizes, even between the older generation DPi of punctures if you guys want it, and they said no, they the next generation and that should bring cars and the new LMDh cars, could pose a want the fastest tyre. They take the risk because they something we don’t have today. This is the problem for the Americans. had three cars and it is less likely to happen to all three. next evolution, the next step, and will be ‘Currently, DPi cars will have less grip,’ ‘Now we can decide what we want, and so we want around for a long time, bringing both stability says Bonardel. ‘The LMDh cars will last longer to try that. It is on road tyres now, so why not on race and cost control. [on fuel and tyre wear]. There will be more tyres? It is a good place to try. ‘We are willing to extend homologation rubber, first, and for DPi we took technology [of DPi] until LMDh is introduced. We haven’t that is close to LMP2. LMP2 is not a What I expect made any formal announcements about confidential tyre, so we don’t want to use the when LMDh will be introduced. The technical best technology that we have because these is that the next team has been focussed on producing what are tyres we disclose, [but] I think the tyres two generation we have announced today.’ for LMDh will be faster and more durable. We On Balance of Performance, there has have to bear in mind that the LMDh car will of tyres will not been a strong dialogue between IMSA and be heavier as well. The DPi is better than LMP2 have a problem the ACO so, although there is no formal [in terms of performance]. How they manage agreement or BoP figures, both organisations the transition from DPi to LMDh is up to IMSA.’ warming up are aware of the other’s requirements. The announcement of the new Matthieu Bonardel, regulations certainly had a positive effect on head of Michelin LMH Active simulation the paddock at Le Mans, but there were also product line ‘We don’t want to make any statements concerns voiced surrounding costs. Although yet, but every step of the way we haven’t the two series will put the cars into a been working in a vacuum,’ said Hodgson performance window that allows them to be ‘Another thing I really want is to get rid of tyre at Le Mans. ‘We have taken into account the balanced, they have to perform to the same warmers. What I expect is that the next two generation requirements of each championship, which high level in all conditions to be competitive. of tyres will not have a problem warming up. The is also driven by LMH and convergence. We Clearly, there is still a great deal of work to do current tyre design is for tyre warmer conditions, have active simulation groups, including before this rule set is final, and before IMSA and if you don’t do that you lose lap time. However, hybrid, so know the capability of our classes throws open the door to LMH to race in the designing a tyre to warm up in cold conditions is going currently at those tracks and that is a baseline US. However, the first couple of tentative to prevent using technology that makes the tyre very for trying to achieve parity of performance. steps have now been taken. grippy when it is warm. It is not as good, and the tyre spends more time warm than cold. So, it is a trade-off you don’t want to do if you face competition. ‘[The tyres] will be a second or two slower. But if I put some research into that, and I decide it is what I want to do, we can reduce the trade-off over the next four years to perhaps zero. ‘The second year is still a big bet because of LMP2. If they overtake the Hypercars [on warm tyres], the championship looks bad. The data says even today with current tyres, with weight, horsepower and what we have in mind, at Le Mans it should be okay. But we have to be careful on slow speed tracks not to reduce performance too much or the LMP2 will be faster. ‘Today, the ACO wants Goodyear to provide tyres that are slower [for the LMP2 class], but why would they do that? The only way to do that is if the ACO says to get rid of tyre warmers. If nobody has tyre warmers and everyone accepts losing one or two seconds per lap, we could stop using them. We have to consider where we are in 10 years. In cars, it deserves a try.’ It’s the end of the road for DPi in 2022 as LMDh is on its way and is expected to arrive mid-season

22 www.racecar-engineering.com NOVEMBER 2020

16-22 REV30N11_Le Mans regs-MPAC.indd 22 23/09/2020 11:27 A NEWNEW DIMENSION IN TRANSMISSIONENDURANCE TECHNOLOGY

SupplyingOur motorsport transmissions and automotive for the seventeen customers top constantly placed finishers atpush this the year’s boundaries Le Mans of 24 high hours performance – including with first more place in allcomplex four categories and demanding – was loadsan emphatic on our family endorsement of ILEV of the organisers’ decision to select our new P1359 hybrid gearbox e-axles and EDU’s. Demands which we match and exceed (pictured) to be the spec transmission in the LMDh category by investing in the finest talent and technology available. for 2022 and beyond. #thinkitmakeit#thinkitmakeit

THATCHAM, UKUK G• INDIANAPOLIS INDIANAPOLIS AND AND MOORESVILLE, MOORESVILLE, USA USA www.xtrac.com INSIGHT – PEUGEOT LMH Stardate 2022

How is approaching its LMH programme By STEWART MITCHELL

24 www.racecar-engineering.com NOVEMBER 2020

24-28 REV30N11_Peugeot Hypercar-MPBSSMAC.indd 24 22/09/2020 20:28 ollowing the ACO and IMSA fi rming up much of the regulations for the newly introduced LMDh class, along Fwith (LMH) at Le Mans 2020, Peugeot Sport and its technical partner, Total, confi rmed that it will be entering the LMH class in 2022, a year earlier than expected. The decision to enter the LMH category was dictated primarily by the aerodynamic freedom allowed in this class, at Stardate 2022 least when compared with LMDh regulations. ‘With LMDh based on current LMP2 architecture, this makes it impossible to incorporate the aesthetic detail of the Peugeot Sport brand,’ comments Peugeot brand CEO, Jean-Philippe Imparato. ‘After launching the various phases of studies for general [LMH] structure, aerodynamic concept and the choice of engine architecture, comes the fi nal decision of the electrical framework, and then that of the conception of the hybrid traction chain. All of the Peugeot Sport technical departments are involved in these development phases.’ Provided a specifi c overall aerodynamic effi ciency is not exceeded, teams developing cars for the LMH category have a good deal of freedom in the 5m long and 2m wide vehicle. Technical director at Peugeot Sport, Olivier Jansonnie, continues: ‘To date, we have confi rmed part of the aerodynamic concept, the engine framework and have chosen the functionality of the hybrid system and its fundamental design. We still have several steps left before we make our debut in endurance in 2022 – in studies, the production of prototypes and, fi nally, affi rmation on the bench and the track. ‘We are not in the building stage yet, we are in the pre-concept phase, starting the design study, which is laying out in CAD the engine, gearbox and wheelbase setting. LMDh regulations have set wheelbase dimensions, [but LMH regulations] have maximum and minimum overhangs and overall dimensions, and you still have some adjustments on the wheelbase.’ Engine choice As per LMH regulations, the Peugeot Sport car will be four-wheel drive, outputting a total of 500kW with a front axle-mounted electric motor with a peak output of 200kW, together with a centrally-mounted, internal combustion engine driving the rear wheels. Engine design for LMH is relatively free, the rulebook only prescribing that petrol four- stroke engines are permitted, with several diff erent levels of technical scope depending The Peugeot LMH is still in the pre-concept, design study phase, while on the constructor’s choice. Manufacturers Peugeot Sport engineers are working on engine and gearbox positions are free to develop a bespoke engine or use in CAD. Unlike LMDh, there is no set dimension for wheelbase in one based on an ‘engine of the make’ series LMH, which makes for a more interesting engineering challenge production power unit, mounted in a car model of the same group and produced in a minimum quantity.

NOVEMBER 2020 www.racecar-engineering.com 25

24-28 REV30N11_Peugeot Hypercar-MPBSSMAC.indd 25 22/09/2020 20:29 INSIGHT – PEUGEOT LMH

For bespoke engines, there are a number of rules designed to prevent escalating Peugeot’s Endurance Racing Record costs at the R&D stage. Amongst them, 2011 ( HDi FAP) only four reciprocating poppet valves with 1st, Intercontinental Le Mans Cup axial displacement are allowed; no more than two inlet and two exhaust valves per 2010 (Peugeot 908 HDi FAP) cylinder; the sealing interface between the 1st, Intercontinental Le Mans Cup moving valve component and the stationary engine component having to be circular; 2009 (Peugeot 908 HDi FAP) 1st and 2nd, Le Mans 24 Hours and electromagnetic and hydraulic valve actuation systems are forbidden. 2007 (Peugeot 908 HDi FAP) Should a manufacturer choose the ‘engine 1st, Le Mans Series of the make’ option, the regulations open up somewhat, including allowing the use of 1993 () 1st, 2nd and 3rd, Le Mans 24 Hours variable valve geometry devices, provided the system remains as designed for the 1992 (Peugeot 905) original engine. The only drawback is in the 1st, Sportscar World Championship minimum volume requirement, which states 1st, Le Mans 24 Hours at least 25 identical engines homologated for a series production road car must have been produced by the end of the year of the fi rst When asked whether the turbocharged, Total also produces a unique endurance season the engine is competing in, and 100 1.6-litre, inline, four-cylinder engine Peugeot’s racing lubricant for the engines and by the end of the second year. partner company, , used in the WRC gearboxes running in Le Mans conditions, With very few other restrictions, this up until the end of the 2019 season would where a 70 per cent wide open throttle load brings the potential for using roadgoing be appropriate for the LMH programme, situation is commonplace. As well as being ‘hypercar’ engines into the fray, which can be Jansonnie responded, ‘With the need to able to cope in these extreme conditions, the far more sophisticated than those prescribed deliver 500kW, we need something more lubricant must be capable of working in an by the bespoke race engine category. signifi cant than that, and Le Mans is a very unusually wide heat range as the race goes diff erent discipline. There will be some carry through night and day. At the high ambient Energy choice over of knowledge, but it is a new engine, and temperatures experienced during the day, the It is a similar story with the ERS and energy all I can tell you at this stage is we are doing lubricant has more diffi culty cooling down, so ‘To date, we have confi rmed part of the aerodynamic concept, store, though the deployment regulations the engine ourselves, in-house.’ the exchange between air and oil needs to be restrict the design and development teams very specifi cally tailored to this environment. the engine framework and have chosen the functionality from going crazy in this area. For the LMH Total involvement It uses a specifi c base oil stock and the cars, the electrical DC power of the MGU-K Total is a multi-energy company, right viscosity must be chosen to ensure the must not exceed 200kW and, except for the incorporating battery manufacturer SAFT, oil thickness is never broken through to the of the hybrid system and its fundamental design’ pit lane, the MGU-K can only apply positive that answers mobility and energy demands bearings throughout the engine. Olivier Jansonnie torque to the front wheels if the speed of the in many sectors, and the Le Mans Hypercar Total has gone to great lengths to reduce car is 120kph or higher when fi tted with dry project is allowing the company to study new the viscosity, as adding a thicker oil fi lm to weather slick tyres, or over 140kph on wets. battery solutions alongside Peugeot. the engine might reduce internal friction, As with the internal combustion engines, According to Philippe Montanteme, Total but causes challenges in evacuating all of the choice of bespoke MGU-K or series strategy / marketing and research director; the oil galleries that feed the mechanical production-based ‘MGU-K of the make’ is ‘The Le Mans Hypercar project provides us parts. Also, if the oil is too thick, the radiators allowed, with diff erent prescriptions for each. with possibilities for joint development on are not able to cool it down quickly enough For teams opting to design and the entire energy system of the car, on the because the heat exchange properties drop manufacture a bespoke system for the effi ciency of our fuels – for all competitors, proportionally with fl uid density. LMH category, the unit must be a single as the exclusive supplier – and for the lube, The trade off with using a highly viscous MGU-K with rotational speed no higher than specifi cally designed for hybrid vehicles.’ oil is oil pressure must be increased to ensure 25,000rpm, a laminate thickness no less than Until 2023, Total is the offi cial fuel supplier the required fi lm thickness on components is 0.1mm and it must be solely and permanently for the FIA World Endurance Championship maintained, though this technique is usual for mechanically linked to a fi xed ratio drive with (WEC), which includes the 24 Hours of Le endurance racing engine applications. a homologated ramp on the front axle. Mans. Total supplies an E20 fuel, 20 per cent The ‘MGU-K of the make’ option has ethanol in petrol, which off ers a higher no such upper rpm, laminate thickness or octane rating (Research Octane Number number of drive units limits, but the same (RON) 105), leading to improved anti-knock ‘It is a new engine, and all homologation rules as engines apply. properties, and a higher oxygen content Jansonnie notes some nuances in the when compared with regular petrol. Those LMH powertrain concept and power delivery: refl ect the current concerns of manufacturers I can tell you at this stage ‘You can’t store enough energy in the battery and motorists of consuming less fuel, and to deliver the [full 200kW] of energy for the reducing their environmental footprint. is we are doing the engine whole lap, you must be selective and deploy This high-octane WEC fuel also makes electric power when most suitable. You need it possible to optimise both compression ourselves, in-house’ to rely on the engine to provide [the full ratios and ignition settings for turbocharged permission of] 500kW at the back, so need to engines, improving their thermal effi ciency Olivier Jansonnie,technical director design an engine to supply that power.’ and increasing longevity. at Peugeot Sport

26 www.racecar-engineering.com NOVEMBER 2020

24-28 REV30N11_Peugeot Hypercar-MPBSSMACBSAC2.indd 26 23/09/2020 11:12 ‘To date, we have confi rmed part of the aerodynamic concept, the engine framework and have chosen the functionality of the hybrid system and its fundamental design’ Olivier Jansonnie

NOVEMBER 2020 www.racecar-engineering.com 27

24-28 REV30N11_Peugeot Hypercar-MPBSSMAC.indd 27 22/09/2020 20:29 INSIGHT – PEUGEOT LMH

Engine oil temperature at Le Mans can ‘The simulation working group is currently reach as high as 150degC, at which point working on defining the energy consumption ‘BoP sets limits, but also some base oils in engine lubricants begin to per lap, giving the cars the same stint break down. To combat this, Total developed duration and aero homologation. These allows room for many a fully synthetic oil with an ester compound definitions should not be something intrusive and mPAO base fluid that has better heat into the design of any cars at this stage as we technical possibilities exchange capabilities than hydrocarbon-base all still have flexibility. fluids and allows for the use of an additive ‘BoP will make sure everyone can be in the in our development, package to reduce friction. The polymers window, that is the game of the BoP. We know in the base fluid do not have high heat that the FIA will do 1:1 scale wind tunnel specifically on the exchange characteristics, but they help on the testing during the homologation process, so high-pressure condition with no effect on the we will be doing the same.’ general shape of the heat release of the fluid. Le Mans also has an issue with oil Development schedule power delivery’ contamination. Even with the robust air filter One challenge facing Peugeot is tyres. systems used on today’s race engines, some Michelin is sole supplier to the category, and Olivier Jansonnie debris makes its way through the combustion has already developed the Toyota family of chamber and into the lubricant. As a result, tyres as its hypercar starts testing this month Total adds a polymer to the oil that surrounds (October). ‘We have no baseline,’ admits bring a car to the track that is reliable and and helps contain these unwelcome particles, Jansonnie. ‘People already involved in LMP1 performs well enough to win at Le Mans. preventing them from adhering to any metal have more experience of the current tyres, ‘We are not underestimating the task,’ parts within the engine. and we are quite comfortable in looking at says Jansonnie. ‘We have a high opinion Total and Peugeot have carried out solutions by simulation, but putting a number of the opposition, and we want to come significant testing to ensure the minimum on the lap time? Right now, we are not going to Le Mans and be ready. The new LMH mileage of any contaminated oil can to be able to do that. will be a homologated car, and you don’t withstand the harshest stint conditions at ‘We have the same concept as Toyota, want to homologate the car too early in the Le Mans. Oil analysis is allowed during the [and Michelin has] one family optimised for development phase and freeze everything in race itself, and is crucial to determining wear four-wheel drive applications. To balance the car before you can improve it. inside the engine during the race and so is other tyre sizes, and with those running rear- ‘The homologation process will be long, widely used by endurance racing teams. wheel drive, will be tricky to set up.’ and you have some milestones of when to The oil capacity of Le Mans racing To compensate for this, Peugeot Sport has disclose information to the FIA first, and then engines is high, often around 50 per cent built up a development schedule that takes finally give more details. The beginning of the more than a road car platform with the them to 2021 for the car’s first test. Many of process doesn’t matter, it is when you come same configuration. This high capacity also the team personnel in the LMH programme to an end, and the FIA freezes your car, that is helps lower thermal loading and stress on are from the 908 project, so know all too well when it is crucial. We will race in 2022, and each molecule of oil as the loads are spread how tough it is to design, build, develop and we will be ready then.’ across much more fluid. A question of Balance LMH incorporates Balance of Performance ‘We have a high opinion of the opposition, and (BoP) between manufacturers in the class, and with the LMDh class. As to whether we want to come to Le Mans and be ready’ the LMH cars will have better acceleration due to their four-wheel driveline, Jansonnie Olivier Jansonnie elaborates: ‘BoP sets limits, but also allows room for many technical possibilities in our development, specifically on the general shape of the power delivery. ‘The concept between us [LMH] and LMDh is different, firstly because LMDh is two-wheel drive and we are four-wheel drive by regulation. Secondly, we have to use an engine that can deliver 500kW. We must therefore accept convergence of performance between LMDh and LMH because, at the end of the day, it will be profitable for everyone. And BoP is supposed to balance everything anyway, so there will not be a big difference between each of the cars. ‘They have to get the BoP right, though, and IMSA has to allow LMH cars to run in the US. They haven’t done that yet, but we expect that to come out of the simulation working group, which we are in the middle of the process at the moment. Peugeot’s previous Le Mans effort was the 908, which developed into the 908 Hybrid4 for 2012, but the programme stalled

28 www.racecar-engineering.com NOVEMBER 2020

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29_1120_RCE.indd 29 23/09/2020 17:52 BALANCE OF PERFORMANCE – INSIGHT Natural science How understanding the physics of vehicle performance is crucial to making BoP changes By SCOTT RAYMOND

When attempting to balance vehicles, what we are really doing is manipulating the ability of a vehicle to generate longitudinal and lateral forces SRO / Patrick Hecq Photography Hecq SRO / Patrick

30 www.racecar-engineering.com NOVEMBER 2020

30-38 REV30N11_BoP-MP2AC.indd 30 22/09/2020 20:34 BoP variables typically include mass, total power output, minimum ride height, aerodynamic elements and tyres. All of these can be related back to physics

When attempting to balance vehicles, what we are really doing is manipulating the ability of a vehicle to generate longitudinal and lateral forces

NOVEMBER 2020 www.racecar-engineering.com 31

30-38 REV30N11_BoP-MP2AC.indd 31 22/09/2020 20:34 BALANCE OF PERFORMANCE – INSIGHT

n previous issues of Racecar Engineering (V29N12 and V30N3) we have discussed several key concepts regarding Balance Iof Performance (BoP). First, it was identified that BoP decisions should not be politically based, and we should not forget about first principles of engineering when analysing the performance of vehicles. Second, we discussed the myriad things that make BoP decision making difficult, with the trickiest issue of all being sandbagging, or performance management (see RE V30N7). With the knowledge of this background information, we can move on to discussing the act of making changes to the Balance of Performance for a group of vehicles. But first, again keeping first principles in mind, we need to ensure we understand the physics problem we are dealing with. Once we understand this, we will move on to look at what options are available for making changes to BoP tables, and how these influence vehicle performance. Equations of motion At the very highest level, the performance of a vehicle around any circuit is subject to Newton’s Second Law, F = ma, coupled with some equations of motion. The description that follows is basically how vehicle dynamics simulations work. Using the SUVAT equations of motion from physics, all vehicle movement on a racetrack Starting with the equations of motion, can be broken down into a set of time intervals with initial and final conditions

the motion of a vehicle around a circuit is Photography Hecq SRO / Patrick dynamic, where the vehicle is travelling through three-dimensional space over time. At this point we need to take Newton’s than the friction force, the block will not If we break this motion through space into Second Law into consideration. From the move. It is only once the gravitational force smaller and smaller time intervals, we can above application of the equations of motion, component is greater than the friction force start to think about the state of the vehicle for we can see that the velocity of a vehicle at that the block will begin to accelerate down each of those time intervals as having a set of any point around a circuit is governed by the ramp. So, acceleration cannot happen initial conditions, and a set of final conditions. the vehicle’s ability to accelerate. Therefore, until the total force – the sum of propulsive When the time intervals are reasonably small, it is best to think of Newton’s Second Law forces minus the sum of resistive forces – is it is possible to approximate the change in expressed in terms of acceleration ie a = great enough. Hang on to this concept as we the vehicle state from initial to final condition F/m. We need to think of this equation as the start applying it to a vehicle. as a constant acceleration problem. Using acceleration equalling the sum of all forces The idea of breaking forces into this approximation, we can apply the SUVAT (total force) divided by the mass. These total directional components definitely applies equations of motion from physics to get forces include those available for propulsion, to the motion of vehicles. In fact, we cannot from the initial vehicle state to the final and those forces resisting propulsion. work with the SUVAT equations or Newton’s vehicle state. SUVAT is an acronym where s For example, a block sitting on an Second Law until we break the forces = displacement, u = initial velocity, v = final incline will have two forces acting on it: a acting on a vehicle into two components. velocity, a = acceleration, and t = time. gravitational force and a frictional force. We need to break the equation a = F/m For now, we will assume we already know The component of the gravitational force into its respective longitudinal and lateral the vehicle’s acceleration so, if we also know that is parallel to the surface of the incline components yielding two equations to work

the initial velocity and time step, we can will act to pull the block down the incline, with: longitudinal acceleration ax = Fx/m, and

apply the second SUVAT equation to calculate but the friction force between the block lateral acceleration ay = Fy /m. Considering the displacement of the vehicle during the and the surface of the incline will resist this the concept of total forces, the longitudinal time step ie s = ut + ½ at2. In addition, we can component of the gravitational force. If the acceleration is equal to the total vector sum apply the first SUVAT equation, v = u + at, to gravitational force component is smaller of all longitudinal forces divided by the calculate the final velocity of the vehicle at the end of the time step. For the following time step, the initial velocity is the final velocity from the previous time step, and The idea of breaking forces into directional from there we can proceed to evaluate each time step sequentially. However, we cannot components definitely applies to the accurately do this until we know what the vehicle’s acceleration is for each time step. motion of vehicles

32 www.racecar-engineering.com NOVEMBER 2020

30-38 REV30N11_BoP-MP2AC.indd 32 22/09/2020 20:34 situation around a constant radius corner. In this scenario, the vehicle corners at a constant velocity that is related to the lateral 2 acceleration through the equation ay = v / R, where v is the constant velocity around the corner, and R is the radius of the corner. We are still dealing with a situation with lateral acceleration resulting from the total lateral force divided by the vehicle mass, and we still have propulsive and resistive forces in lateral direction. The propulsive force, or the force that is driving or pushing the vehicle towards the instantaneous centre of curvature, comes from the ability of the vehicle’s tyres to generate a lateral force between the tyre and road. This is essentially a frictional force that increases as the vertical load on the tyres increases. The resistive force comes from the inertia of the vehicle. Like all bodies in motion, the vehicle does not want to turn because it wants to keep travelling along happily in a straight line. This inertial force wants to push the vehicle back to travelling straight, so it pushes it away from the instantaneous centre of curvature. When the lateral force from the tyres equals the lateral force from inertia, the vehicle is balanced and can travel around the curved path. If the inertial force exceeds the available tyre force, the vehicle leaves the curved path, which often ends spectacularly poorly for the occupants of the vehicle. When the inertial force is less than the lateral force potential of the tyres, the vehicle can speed up and travel If the inertial force exceeds the available around the corner faster, or take a smaller tyre force, the vehicle leaves the curved radius line around the corner. Combined acceleration path, which often ends spectacularly On the topic of combined forces, where you have both lateral and longitudinal vehicle poorly for the occupants of the vehicle accelerations, or lateral and longitudinal tyre forces, we are really talking about the ability of a tyre to generate combined force. A tyre vehicle mass, and the lateral acceleration is This is not the only force we need to consider is just a big elastic, and an elastic generates equal to the total vector sum of all lateral here, though. Just as there was a frictional force when it is stretched. Unfortunately, an forces divided by the vehicle mass. force resisting motion of a block on an elastic can only stretch so far before it fails. incline, there are several forces that resist the Longitudinal forces stretch the tyre parallel Longitudinal acceleration propulsive force from the engine and tyres. to the direction of travel, while lateral forces

The longitudinal acceleration, ax, is the These resistive forces include frictional losses stretch the tyre perpendicular to the direction acceleration we feed into the SUVAT from within the drivetrain, rolling resistance of travel. The total stretch, or total force the equations and is the only acceleration from the interaction of the tyres with the tyre can generate, is the vector sum of the we need to consider when looking at a road surface, aerodynamic drag and any lateral and longitudinal components. straight-line acceleration problem. We know applied braking forces. This concept is demonstrated through the longitudinal acceleration is the sum of a tyre’s friction ellipse, where the outer limits longitudinal forces divided by the vehicle Lateral acceleration of the ellipse define how much combined

mass. The longitudinal propulsive force for a The lateral acceleration component, ay, does stretch / force the tyre can handle. When vehicle comes from the vehicle’s power unit. not directly impact the SUVAT equations, the combined force exceeds this boundary For a typical internal combustion engine, but it does indirectly impact them in that limit, the tyre either loses grip by snapping the engine’s output torque is fed through the longitudinal acceleration of a vehicle back to a less strenuous amount of stretch, a drivetrain (clutch, driveshaft, gearbox, is limited by the total possible combined or fails where the rubber in the contact patch differential, axles, hubs and wheels) to the acceleration ie the vector sum of the lateral literally falls apart. The point here is that for vehicle’s tyres. This torque acting through and longitudinal acceleration. Before we a given amount of lateral force, a tyre can the tyres results in a force parallel to the road consider combined acceleration or combined only generate a fraction of the maximum that attempts to drive the vehicle forwards. forces, first think about a pure cornering possible longitudinal force.

NOVEMBER 2020 www.racecar-engineering.com 33

30-38 REV30N11_BoP-MP2AC.indd 33 22/09/2020 20:34 BALANCE OF PERFORMANCE – INSIGHT

Even when BoP is done successfully, drivers and teams still have to manage tyre wear throughout a race and performance changes according to conditions, set-up, driving style and pre-race preparation

Returning to the SUVAT equations, we can Diff erent racing series have diff erent now see how lateral force and acceleration options available to adjust performance The physics discussion impact the available longitudinal force of vehicles, but the general BoP variables a tyre can generate, which in turn limits typically include mass, total power output, helps us link parameter the longitudinal acceleration available to minimum ride height, aerodynamic elements, calculate the distance travelled and fi nal fuel capacity and, to some extent, tyres. changes to the primary velocity of each time step. Why have we spent this much Mass modes of operation of a space discussing the physics of vehicle As implied by Newton’s Second Law, the mass performance? How is this related to Balance of a vehicle directly, and inversely, impacts vehicle around a circuit of Performance? Well, Balance of Performance the ability of a vehicle to take advantage of is simply a physics problem. When attempting the propulsive forces to accelerate. Whether to balance vehicles, what we are really doing we are talking about longitudinal or lateral Total power output is manipulating the ability of a vehicle to accelerations, any increase in mass will reduce As we discussed already, a vehicle’s power generate longitudinal and lateral forces, the acceleration capacity in those directions, unit is responsible for generating its which in turn determines how the vehicle while any reduction in mass will improve the longitudinal propulsive force. This force, when accelerates longitudinally and laterally. I acceleration capacity of a vehicle. all the resistive forces are overcome, is what really want to emphasise this point strongly Because of the direct impact of mass on drives the vehicle forwards though space, because, if we think of BoP as a physics longitudinal and lateral accelerations, we and defi nes how quickly the vehicle can problem, we can begin to have a much can increase a vehicle’s mass to slow it down accelerate longitudinally. A higher capacity better understanding of how changes to or reduce a vehicle’s mass to speed it up. A for longitudinal acceleration leads to a vehicle parameters will infl uence the overall good rule of thumb is that a 10kg increase or reduction in lap time, while less acceleration performance of a vehicle. And the better we decrease in mass will result in a 0.15 per cent capacity yields a slower lap time. understand the physics, the better we will increase or decrease in lap time, respectively. There are many confi gurations of power be at making changes! So, on a 100-second lap, 10kg will have a unit encountered in racing, normally 0.15 second impact. aspirated internal combustion engines, turbo Options for changes Before we leave the topic of mass, think / supercharged internal combustion engines, With the physics behind us, we can now look about how mass then infl uences the lap hybrid engines and fully electric motors. I am at what parameters we can change, and time of a vehicle as far as fuel is consumed. A going to focus here on normally aspirated think about how these parameters infl uence vehicle with a 100l fuel tank will be carrying and turbocharged engines. the performance of a vehicle. The physics approximately 72kg of fuel at the beginning With normally aspirated engines, the discussion helps us link parameter changes of a stint. By the end of the stint, and total power output is primarily controlled by to the primary modes of operation of a assuming no tyre degradation, this vehicle inlet air restrictors with a specifi ed minimum vehicle around a circuit, travelling in a should be approximately 1.08 per cent faster diameter. These control how much air fl ows straight line and cornering. (again, on a 100-second lap). into the engine, which in turn determines

34 www.racecar-engineering.com NOVEMBER 2020

30-38 REV30N11_BoP-MP2AC.indd 34 22/09/2020 20:34 Untitled-61 1 30/06/2016 13:22 BALANCE OF PERFORMANCE – INSIGHT

how much air is available to mix with fuel in that the limit has an impact across the for combustion. Increasing the minimum entire rpm range. A boost limit curve allows With boost limit curves, diameter of a restrictor increases the volume a sanctioning body to shape the power of air that flows into each combustion output across the rpm range. With boost limit it is possible to add or chamber, which means a higher volume curves, it is possible to add or subtract power of fuel can be mixed with the air, and a where it is needed, which is a highly desirable subtract power where bigger explosion can be created. So, a larger function from a BoP perspective. restrictor diameter equals more power, while it is needed, which is a smaller one equals less power. Fine tuning Engine restrictors come in two varieties, In my personal experience, I have been able highly desirable from a sonic and non-sonic. Sonic restrictors have a to successfully align the power outputs of continuously curved profile along the length normally aspirated and turbocharged cars BoP perspective of the restrictor – much like the outlet of a by first ensuring the power outputs of the trumpet – where the minimum diameter is normally aspirated cars are matched using found somewhere along the curved profile. inlet air restrictors, and then fine tuning the lap time (once again, on a 100-second lap). Non-sonic restrictors typically have a conical output power of the turbocharged cars by Of course, this factor is highly dependent on inlet and outlet with straight walls and a tuning their boost limit curves. the circuit layout, as there are circuits that are flat cylindrical central section where the Engine power output is influenced by much more sensitive to power than others. minimum diameter is found. A small radius several other factors that may be used to is applied where the straight walls meet the balance vehicle performance. For example, Minimum ride heights flat cylinder, and the length of the cylinder sanctioning bodies may specify ignition We say ‘minimum’ ride height because a is prescribed by the sanctioning body. Non- angles to increase or reduce spark advance sanctioning body will typically want to try sonic restrictors will influence the output and impact the engine’s power output. and restrict a car from going any lower than power over the entire rpm range, while sonic Likewise, an air / fuel ratio (lambda) may be the minimum prescribed ride height. These restrictors only reduce power once the air specified to control the fuel delivered to an ride heights are typically static, so there is flowing through the restrictor starts to choke engine to add or reduce power. nothing stopping the vehicle from going at higher engine rpm. In cases where the engine ECU is locked lower dynamically while on track. The power output for turbocharged or cannot be reprogrammed, it is possible Unfortunately, minimum ride height engines is typically controlled by a boost to increase or reduce maximum rpm limits regulations can have unintended limit, or a boost limit curve where increasing to control power output. If this cannot be consequences on vehicle set-ups. Teams may boost pressure results in a power increase programmed into the ECU, this would involve start to introduce elaborate bump rubber, and reducing boost pressure reduces a team setting the shift lights higher or spring and damper settings as a way to output power. A boost limit applies a single lower and the sanctioning body scrutinising pass the minimum ride height rules during maximum boost level across the entire the shift rpm through further data analysis technical inspection, but to still achieve a engine rpm band, while a boost limit curve following a session or event. desired dynamic ride height while on track. assigns a maximum allowable boost as a For a 500bhp vehicle, a good rule of Ride heights have several impacts function of engine rpm. A boost limit acts thumb is that a 10bhp change in power on vehicle performance. For all vehicles, in a similar manner to a non-sonic restrictor output will result in a 0.31 per cent change in increasing or decreasing the minimum ride height will impact the c of g height of the vehicle dynamically. An increase in c of g height causes increases in lateral and longitudinal load transfer when accelerating laterally and longitudinally. Increased load transfer tends to degrade vehicle performance because of the influence it has on the vertical tyre loads when accelerating. For example, a higher c of g in cornering causes a significant reduction in the vertical load acting on the inside tyres that acts to reduce the total lateral force the tyres can generate across the axle. As we have already seen, a reduction in lateral force on the tyres reduces the lateral acceleration capacity, which results in a slower cornering speed. For aerodynamic cars, changes in ride height influence both the total downforce and the total drag. In most cases, increasing ride height causes a reduction in available downforce. This then has an impact on the vertical loads on tyres acting to reduce the lateral or longitudinal force the tyres can generate. The opposite is true for reducing Even the tyre manufacturers themselves have to be careful not to cool or cook tyres in transit to the ride heights. So, increasing minimum ride track as either one of these conditions can have a fundamental effect on the racecars’ performance heights can have the effect of increasing lap times due to reduced aerodynamic forces.

36 www.racecar-engineering.com NOVEMBER 2020

30-38 REV30N11_BoP-MP2AC.indd 36 22/09/2020 20:34 GARMIN CATALYST™

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On aerodynamic cars, BoP can be achieved by adjustments in minimum ride height, which has an attendant effect on downforce and drag, and consequently lap time

The combined c of g and aerodynamic power, there are circuits that favour higher The impact of effects of minimum ride heights make it downforce at the expense of increased drag. extremely difficult to have any sort of rule of Another simple element that can be thumb for these changes. changed to influence downforce and drag various aerodynamic is a wing wicker or Gurney. In most cases Aerodynamic elements an increase in Gurney height increases drag elements on lap time Aerodynamic devices are often used to while increasing downforce. I have used control the downforce or drag of a vehicle. Gurney height as a tool to manage a vehicle’s is highly specific to Downforce has an impact mostly on the top speed on several occasions. cornering and combined acceleration each device components of a circuit, while drag mostly Highly specific impacts the straight-line speed of a vehicle. The impact of all the various aerodynamic While we’ve already addressed the elements on lap time is highly specific to each far one can go, and both have a big influence, influence of ride heights, the aerodynamic device, so again it is exceptionally difficult to but it is important that everyone is on a level properties of a vehicle may be changed with have any kind of general idea that may be playing field to start with. wing angles, wickers or Gurneys, dive planes, applied to most situations. splitters and the myriad other potential Tyres aerodynamic elements that may be attached Fuel capacity Tyre dimensions and specifications are to or removed from the vehicle. There is Fuel capacity is perhaps the exception here as not something that change often in BoP usually no free lunch with aerodynamic it does not fit very well with the discussions tables, but these changes may still occur. For devices, so you cannot add more downforce on Newton’s Second Law, but it does have a example, I have experienced times when without increasing drag, or reduce drag significant impact on the outcome of races. a new tyre for a car simply does not work without reducing downforce. So, this needs to Fuel capacity defines how far a vehicle can go with the vehicle, and a reversion to an older be taken into consideration when modifying between pit stops. In many cases, especially specification was required. In addition, I have the aerodynamic characteristics of a vehicle. where tyre warmers are not allowed, there are seen changes to tyre specifications where the For properties such as wing angles, a significant gains to be made by going one or tyre dimensions are increased or reduced to sanctioning body may prescribe a range in two laps further on fuel stint. influence the cornering capacity of a vehicle. permissible angles, or define a minimum Likewise, in series where full course Again, these changes are rare, but they do allowable wing angle. In general, increasing yellows can interrupt green flag running, occur so should still be noted. a wing angle acts to increase the downforce there is a definite advantage to being In Part 2 of this feature, we will expand on a vehicle while also increasing the drag. the first car to pit last. As such, teams and upon the base knowledge we have covered Whether or not this change makes the car manufacturers demand equality when it in this article and start to look at what it takes faster or slower depends on the sensitivity of comes to how far they can travel on a full tank to understand when changes are required, the circuit to changes in downforce and drag. of fuel. Of course, driver technique and fuel and what changes are made to solve specific As there are circuits that favour higher engine maps still come into play to determine how Balance of Performance problems.

38 www.racecar-engineering.com NOVEMBER 2020

30-38 REV30N11_BoP-MP2AC.indd 38 22/09/2020 20:34 Ÿ Integral microprocessors Aerodynamic Pressure Scanning Ÿ Direct digital output rEVOLUTIONised

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NOVEMBER 2020 www.racecar-engineering.com 39

45_1120_RCE.indd 45 22/09/2020 15:53 RACECAR FOCUS – INTERSCOPE IP-1 Inch pincher With partner, Interscope Racing, Porsche entered the 1980 Indy 500 to win it, but a matter of inches dictated it never even made it to the grid By WOUTER MELISSEN

40 www.racecar-engineering.com NOVEMBER 2020

40-46 REV30N11 Interscope Porsche-MPAC.indd 40 22/09/2020 20:50 It had fallen victim to a combination Inch pincher of Porsche being Porsche and Indy being Indy

n 6 December 1979, Porsche’s One of the few motorsport arenas in methanol, just to see what eff ect it would director of public relations which Porsche had not achieved success, have. While the results were promising, and sports, Manfred Jantke, the German manufacturer sent a delegation Both’s engineers returned their focus to Oinvited the German media to to the 1977 edition of the Indy 500. It was a further development of the 935 engine the Intercontinental Hotel in Stuttgart to already decided that Porsche would enter for the latest evolution of the 936 announce the plan to compete in the 1980 American single-seater racing, but only as , and the all-new 935 ‘Moby edition of the Indy 500. an engine supplier to an existing team. Dick’ car. This engine was quite a For the German manufacturer’s fi rst departure from the design that had already foray into American single-seater racing, Back burner proven so successful. long-time customer, , and his During the previous couple of years, While the production-based Interscope Racing team was chosen as Porsche’s Can-Am partner, Penske, had and air-cooled cylinders were retained, a partner. Porsche would supply the engine sent regular briefi ngs to Weissach, in completely new head was developed. Not and gearbox, while Interscope Racing would particular on the performance of the then only did it have twin overhead design and build a chassis for it. dominant Off enhauser four-cylinder engine. and four valves per cylinder, it was also A few days later, Jantke spread the But, for a variety of reasons, the dream water cooled. The change in cooling same message to the American press at partnership with Penske at Indy did not philosophy was both a requirement for the an event in New York. However, come May materialise, and the project was temporarily additional and valves and because 1980, there was no sign of the promised placed on the back burner. packaging was so tight that Porsche’s tried Interscope Porsche Indy car. It did exist, Out of sheer curiosity, in late ’77 the and trusted air cooling would not suffi ce. but it had fallen victim to a combination of engineering team led by Helmut Both This particularly aff ected the spark Porsche being Porsche and Indy being Indy. did run a 935 engine on Indy’s mandated plugs, which were moved from the airfl ow

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40-46 REV30N11 Interscope Porsche-MPAC.indd 41 22/09/2020 20:51 RACECAR FOCUS – INTERSCOPE IP-1

Sharp nose and fully shrouded suspension was designed to allow clean airflow through to the tunnels beneath the full-length sidepods

into the area between the camshafts. Both’s Like AAR, Interscope Racing was based methanol also required a much higher fuel engineers did find time in their already busy in Santa Ana, California and, while the flow, for which even the injection pump of schedule to also try this engine on methanol ‘Interscope IP-1’ was being readied, the the 917 did not suffice. Bosch stepped in and as well, just in case. team modified one of its existing Parnellis developed a fully electronic injection system. With the new 24-valve engine in the back, to house the engine under development at the Porsche 936 could not quite take a third Porsche in Weissach. Although several years Pressure point win in a row at Le Mans in 1978, and Porsche old at this point, the Parnelli chassis was still As per regulations, the 935/72 flat six was decided to wind down its factory Sportscar competitive, underlined by Ongais’ fourth- fitted with a single Garrett . racing effort at the end of the season. This place finish at the 1979 Indy 500, using the The big question that remained during the freed up time and resources to take another Cosworth DFX V8. development of the engine was at exactly look at the Indy 500. what intake boost pressure the regulators Codename 935/72 would allow it to run. In unrestricted form, it Suitable partner Back at Weissach, the Hans Mezger-lead team, was capable of churning out over 900bhp. Before any further work was done, the which included engineers Helmut Flegl and No ‘six’ had been used at Indy since the first task was to find a suitable partner to Valentin Schäffer, started the development early 1950s, so there had been no reason to build and run the car for the proposed Indy of the new Indy engine, codenamed 935/72. set a figure. This was measured in inches of engine. Penske was committed to Cosworth’s As that name suggests, it was a development mercury and the Offenhauser ‘four’ could new DFX V8, so instead, California Porsche of the flat six that powered the successful run at 60, while the Cosworth DFX V8 was distributor, Vasek Polak, pointed the and 936 racers. First order of business restricted to 48. Working on the assumption people toward Interscope Racing. The team was to bring the engine down to the 2,650cc that their new engine would fit smack in ran a Parnelli chassis with Cosworth power displacement limit set by Indy regulations. the middle of the two, Porsche’s engineers at Indy in 1978 for . More The bore was 92.3mm, stroke was 66mm. expected their ‘six’ could be run at 54in of importantly, Field and Ongais already had What the earlier experiments with mercury. As it turned out, nothing at Indy is a Porsche connection, running 935s in the methanol had revealed was the fuel was quite so straightforward. American IMSA series. At the start of 1979, considerably more corrosive, so some The first 935/72 engine was shipped to they added to their credentials by winning components had to be constructed from the Santa Ana workshop in the autumn of the Daytona 24 Hours outright in their latest different materials, or specially coated to 1979. It was mated to a purpose-built Porsche 935, with Porsche’s as the withstand the effects of this. gearbox with Hewland internals. The casing third driver in the winning car. An advantage of methanol, of course, is featured all the necessary subframe mounting What Interscope Racing promised was a it runs considerably cooler than petrol. points to install the engine. This was a special purpose-built chassis that would be ready To such an extent that the auxiliary fan requirement as the Porsche flat six could in time for the 1980 Indy 500. Hired to help usually used to cool the cylinders could be not be used as a stressed member, like the design the car was Roman Slobodynskyj. eliminated entirely. As on the 935/78 and 936, Cosworth DFX. The weight of these additional The Ukrainian-born engineer had been the cylinder heads were water cooled. structures was offset by the fact the compact responsible for several successful racers Knocking was less of an issue too, which flat six was 60lb lighter than the DFX. during the 1970s, including the 1973 Indy allowed compression to be raised by two The Porsche-engined Parnelli was 500-winning All American Racers (AAR) Eagle. points to around 9.5:1. The change to wheeled out for a first two-day test at the

42 www.racecar-engineering.com NOVEMBER 2020

40-46 REV30N11 Interscope Porsche-MPAC.indd 42 22/09/2020 20:49 The twin ground effect tunnels could better be seen from the rear, exiting either side of the equally shrouded gearbox

In unrestricted form, [the 935/72 engine] was capable of churning out over 900bhp

Designed by Roman Slobodynskyj, the Interscope IP-1 was a radical departure from the Parnelli chassis it replaced

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40-46 REV30N11 Interscope Porsche-MPAC.indd 43 22/09/2020 20:49 RACECAR FOCUS – INTERSCOPE IP-1

The very clean lines were a reflection of the ground-effect revolution that had kicked off in Europe a few years earlier

Ontario oval on 10 October. Ongais, true to his Danny ‘on-the-gas’ nickname, went straight out and clocked a fastest lap of 197mph. This was a promising start, and prompted Porsche to free up more resources. At that first test, the engine ran on 72in of mercury as the final figure was still not 2650cc flat six was a development of the succesful Porsche 935 / 936 engine, but with raised compression and fed methanol clear. It was a subject of debate between more than two parties as Porsche’s entry into North American racing coincided with the falling out between the newly formed Championship Teams (CART) and the (USAC). The regular season races now fell under the stewardship of CART, while the crucial Indy 500 was sanctioned by USAC. This was the race Porsche wanted to win above all, so the conversation over boost pressure took place with USAC president, Dick King. He was keen to put up a good show and also to support the smaller teams that could not afford the expensive DFX engine. This is why the readily available Offenhauser engine was allowed to run at a relatively high level of boost. Memory game However, with Porsche’s championship- destroying campaigns in Can-Am and IMSA still fresh in their memory, King and the rest of Rear bodywork of the car was so low that the upper suspension wishbones actually ran above it USAC were not inclined to giving the German manufacturer too much leeway. Appointed to liaise with King was Porsche’s North American Motorsports chief, Jo Hoppen. In order to keep close tabs on exactly what was happening at Weissach, King requested further information on the engine Porsche intended on running. Initially, he received some very basic drawings that Helmut Flegl had passed on to Hoppen, with the promise of more detail to come. Flegl did send performance figures to Hoppen, but these never made it to King, which left the Americans warier still, and explains why it took so long for a final boost figure to be set. While the political game was played, back at the Interscope facility in Indiana, the first of the purpose-built racecars was being readied. Designed by Slobodynskyj, it was a complete departure from the design of the Parnelli used by the team previously. The very clean A single Garrett turbocharger was used, but it all hinged on the intake boost pressure the 935/72 engine was allowed to run

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40-46 REV30N11 Interscope Porsche-MPAC.indd 44 22/09/2020 20:49 NOVEMBER 2020 www.racecar-engineering.com

61_1120_RCE.indd 61 22/09/2020 16:57 RACECAR FOCUS – INTERSCOPE IP-1

lines were a reflection of the ground-effect revolution that had kicked off in Europe a few years earlier. Accordingly, the Interscope IP-1 featured a sharp nose to allow for a clean airflow to the tunnels mounted underneath the full-length sidepods. The front suspension was fully shrouded, while the rear bodywork was so low the top wishbones ran above it. The tail was dominated by the two ground- effect tunnels either side of the gearbox. Testing with the Parnelli chassis resumed in January, with the engine now running at the proposed 54in of mercury boost pressure. Although these were private tests, some rivals went as far as to hire a helicopter to see what Porsche was up to. Ahead of his final decision, King proposed to send a delegation to Weissach and asses the engine development at the factory. Porsche agreed, but was more than a bit surprised to find one of the delegation members was the engine man of the rival AJ Foyt team. The Germans showed the Up to four IP-1 chassis were constructed, but none ever raced at Indy with Porsche power. This is the only known example American delegates an engine running on the dynamometer, which produced 574bhp It was decided to resume testing in July, Porsche… was more than with 54in of boost. This was an output the engine now mounted in the Interscope that matched the rival engine, so Porsche chassis. Porsche even reputedly considered engineers figured the matter had now been running the car in a race at Mid-Ohio, but that a bit surprised to find one resolved once and for all. was later called off. Testing continued on into September, of the delegation members Development room and the Porsche-powered Interscope was Early in March, the matter was indeed really coming on song. Meanwhile, back at was the engine man of the resolved, but not to Porsche’s liking. The USAC Weissach, a new short-stroke engine was also set the boost level for the Porsche engine drawn up, which should be able to perform rival AJ Foyt team at 48in of mercury, the same figure as the better with the lower boost level. Sadly, the Cosworth DFX V8 that had been designed Porsche board had seen enough by this point, from the ground up as a racing engine, and decided to suspend the Indy programme pit stop forced him to claw back up the order and some six inches less than the Porsche indefinitely in October of 1980. and take one risk too many. Over-correcting engineers had been expecting. King reasoned a slide, he hit the wall head on and destroyed there was sufficient room to develop the Great things the car. He was lucky to come out of the crash Porsche engine further for it then to be as For Porsche, the whole saga turned out not to with nothing more than concussion and competitive as the DFX. be a complete waste of time. A development badly broken legs and feet. Should the performance of the Porsche of the 935/72 engine was destined for truly He returned the following year but, engine turn out to be not at the same level as great things. Modified to run on petrol once once again, suffered a near career-ending its rivals during the races, USAC promised the again, and re-fitted with a cooling fan, it crash after starting from the third row this decision could be reconsidered. appeared the following year in the back of a time. That was the final appearance of the King’s decision was a devastating blow pair of Porsche 936s entered in the 24 Hours Interscope chassis, as the team switched to to the programme. At 48in of mercury, the of Le Mans. Now known as the 935/82, the March chassis from 1983 onwards. engine would produce no more than 540bhp, 2.65-litre engine powered the 936 shared by Long believed to be lost, one of the which would leave the team playing catch and Derek Bell to the outright win, remaining Interscope chassis was discovered up at the back of the field. For a company like with a 14-lap margin over the nearest rival. in a shed in Santee, California by a German Porsche, that was not an option. The ‘Indy engine’ was then fitted in the 956 enthusiast in 2008, still fitted with the In truth, there was some merit in King’s racer that was introduced in 1982. ancillaries to house the Porsche engine. suggestion that – in theory at least – a flat-six The rest, as they say, is history. Finding one of the 10 935/72 engines built engine could perform better with further Porsche did have another go at Indy a proved even more difficult and took several development. This would, however, entail a decade later, but once again with little luck. years. The restoration was further delayed complete redesign of the engine, with the The Interscope team was left to pick up by a lack of documentation, but it was finally engineers effectively starting again from the pieces. It is believed as many as four IP-1 completed in 2020. scratch. Porsche was not inclined to do this chassis had been manufactured by the time The car shown here is believed to be the for a variety of reasons, including a lack of Porsche pulled the plug and so, for the 1981 only Interscope Indy car in existence, and time and resources. Consequently, on 23 season, the team switched back to Cosworth certainly the only fully functional, Porsche- April, Porsche officially announced its entry DFX power. This allowed Ongais to run at engined example. Intended to run at the now into the 1980 Indy 500 had been scratched. Indy once again, an opportunity he relished. cancelled 2020 Goodwood Festival of Speed, After Le Mans, when the dust had settled He qualified on the seventh row and, by lap the car is currently for sale with German a little bit, the programme was re-assessed. 63, was in the lead. A delay during the next dealer KW - Klassische Automobile.

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40-46 REV30N11 Interscope Porsche-MPAC.indd 46 22/09/2020 20:49 C

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47_1120_RCE.indd 47 23/09/2020 16:23 TECHNOLOGY – THE CONSULTANT Sunshine on leaf Hop, squat, lift, wrap and other issues in leaf spring, live axle rear suspension

By MARK ORTIZ

I am building a ‘somewhat vintage reproduction’ track car for the Barber Road Course. It would be best compared to the Camaros and Mustangs that raced the Trans-Am circuit in 1969-’70. The brake package and front steering / suspension is modern and very robust. However, the rear suspension is slider- mounted, 200lb/in, Chrysler-style stacked leaf springs with a (though I plan to try a composite monoleaf at some point in time). The sliders on the rear of the springs will give me up / down and / or angular adjustment, and are within the rules. Bird cages / links and fl oating calipers seem unnecessarily complicated to me and are more than I want to deal with, or package on this car. I know there are probably better ways to skin the cat, but I have always had a fascination with leaf springs and the tuning thereof (ie changing wheel rate / linearity etc. by changing mount geometry The questioner’s ‘somewhat vintage reproduction’ road course car uses slider-mounted, Chrysler-style leaf spring packs and the possibility of ‘tuning’ wheel rates without changing the springs). have something to do with the ‘wheelbase springs are toed in that gives compliance I have been warned that brake hop eff ect’ or is it just race mythology? oversteer. It also can create steer eff ects could be an issue (?) and so, having With its Ford Windsor ‘N’-type engine when a sloped Panhard bar creates lateral talked to the engineers at Landrum and (about 580bhp) and a Roltec synchronised axle movement, as with truck arms. Hypercoil, have included brackets for 4-speed, the car should be about 2700lb, Eliminating the lateral compliance in ‘anti-hop’ shocks. These will allow for with 50/50 distribution, adjustable brake the shackles is the usual reason for using two shocks per rear assembly for up / bias and 12.19in GN6-type front brakes. sliders, and also the reason for adding a down and either one or two, probably What are your thoughts on this set-up? Panhard bar. It is unusual to do both as you 90/10s, to ‘anti’ the brake torque. don’t want two methods of lateral location Some guys swear a leaf set-up will induce fi ghting each other and creating a bind. rear-end steer ie the more loaded side of THE CONSULTANT You can make sliders adjustable for the car will have a longer wheelbase than Certainly, you can get rear roll angle, and also height, although the few the less loaded side. Supposedly, non- steer with leaf springs, just as slider set-ups I’ve seen were fi xed. You parallel leaf springs enhance this eff ect. you can with links. It’s mainly a can do the same with shackles, though. Although, I would add that Bobby matter of how high the front eye Mechanisms with sliding contact tend to Allison had the track record at is with respect to the pad on the axle, plus the have more friction than things that move Huntsville Speedway (asphalt) from characteristics of the spring itself. rotationally about a pivot, and are more about 1975 to 1985 with a quarter As for having the springs non-parallel vulnerable to jamming from dirt and gravel. elliptic leaf spring set-up, and everyone in top view, I don’t think that necessarily One eff ect of the short front, long rear said that was a rear-end steer car. aff ects roll steer, but it aff ects compliance Chrysler-style spring is it gives some anti- Then there is the esoteric ‘bite eff ect’ steer. Leaf springs are laterally compliant, squat and anti-lift. A spring with similar that some claim a leaf set-up has. Does this especially with shackles, and if the front and rear portions acts sort of like Leaf springs are laterally compliant, especially with shackles, and if the springs are toed in that gives compliance oversteer

48 www.racecar-engineering.com NOVEMBER 2020

48-49 REV30N11 Consultant-MPbsAC.indd 48 22/09/2020 21:14 parallel trailing links, with soft rubber changes per inch of travel. To do this with bushings. The Chrysler style acts like the springs in place, you’ll have to find a way CONTACT trailing links that converge toward the to hold the car down. Ordinarily, you do this Mark Ortiz Automotive is a chassis front, again with soft rubber bushings. with the springs out, but of course when the consultancy service primarily serving oval track and road racers. Here Mark answers The usual idea with horizontal shocks springs locate the axle that’s not possible. your chassis set-up and handling queries. above the axle is to damp spring wrap-up. To get the best approximation of what you If you have a question for him, please don’t They are also used to damp oscillations have at static ride height, take a one-inch hesitate to get in touch: in link suspensions with soft bushings, interval from ½in droop to ½in bump. Divide E: [email protected] as on some Fox-body Mustangs. 57.3 or 180/pi by the number of degrees of T: +1 704-933-8876 That can be one cause of wheel hop pinion angle change. That’s the horizontal A: Mark Ortiz in braking, but another can be having a length of your effective side view swing 155 Wankel Drive, Kannapolis lot of anti-lift. Chrysler-style springs give arm, or horizontal distance from the axle NC 28083-8200, USA more anti-lift than others, for the same centre to the side view instant centre. reason they give more anti-squat. Now you also need the height of that The relatively rigid front portion of instant centre. To find this, you need a way the spring acts a bit like a ladder bar. to measure longitudinal (x axis) translation wheel hop. Note that wheel hop from of the axle as you jack it up and down (dx / this cause can’t necessarily be solved Side View Instant Centre dz). This may be a pretty small movement. by damping spring wrap-up. Without some computer programme that Probably the cheapest and easiest way is to probably exists but I don’t have it, you can’t place a machinist’s scale on the floor and drop Bite effect know exactly how much anti-squat and a plumb bob to it from the front or back face Regarding the ‘bite effect’ you mention, I anti-lift your springs will give you when of the axle tube. From this you get inches of don’t rightly know. I interpret ‘bite’ as the you’re designing your system. However, I forward or rearward translation per inch of ability to apply throttle without wheelspin. do know a way to find out what effective vertical travel. That number is also the slope The quarter elliptic set-up you mention? side view instant centre (SVIC) your system of a line from the axle centre to the instant Was it perhaps a leaf car with just the top produces, once you’ve got it assembled centre, upward if the axle moves back in leaves, but a stack on the front half of the left on your frame, and that will tell us how compression, downward if it moves forward one, and coils or coilovers mostly supporting much anti-squat and anti-lift you have. in compression. The SVIC lies on that line, the car? I’ve seen that done successfully on To do this, measure your pinion angle gain, at the horizontal distance forward that you a WISSOTA modified. That produces what just as you would measure camber gain on measured per the preceding paragraph. some might call a ‘bite effect’ ie under power, your front end – put an angle finder on the Armed with those measurements, it it gives strong anti-squat at the left rear, companion flange, or any convenient surface. is possible to tell how much anti-squat adding ‘bite’ in the sense of wedge or diagonal Then jack the whole axle up and down, and anti-lift you’ve got in a suspension percentage. The effect is similar to the and measure how much the pinion angle system, and whether that’s apt to cause offset torque arm on a Super Modified.

accept this diagram is from memory, and you note the rear housing may have been on the top side of the spring, with the spring arched Idownward, rather than as per the illustration. That said, the quarter-elliptic set-up as you have drawn it here would not work. It would fail the lower leaf instantly. You can run cantilevered quarter-elliptics with the thick end clamped to the frame, but you have to have an eye at the axle, and at least one additional link to react torque, so that torque loads the spring in tension or compression, not bending. That’s assuming two springs, one on each side of the car. To use the spring to react torque in bending, you must have the thick part at the axle, where the bending moment is greatest. Even then, you cannot clamp the thin end of a leaf spring as you will have a bending stress concentration at the edge of the clamp. You must have an eye or a drop link at the thin end – something that can pivot. Even sliders have to have those pins that can rotate in the slots, or an eye with a bushing. The systems used on large trucks, at least currently and recently, have a spring on each side, each having two or three really thick Do not copy this, it will not work without an eye at the axle and at least one additional link leaves with the thick end clamped to the axle. The spring has an eye at the front end with a big, soft rubber bushing. The spring extends air springs are connected and therefore cannot resist roll, although behind the axle and serves as an air bag mount, and it is the air bags they damp it somewhat. There is also a very high-mounted Panhard mainly that support the truck. In this situation, the leaf spring serves bar for lateral location. as a sort of compliant ladder bar. These truck suspensions provide a lot of anti-squat and anti-lift. The whole set-up also acts as an anti-roll bar. As with other ladder The truck can be seen to jack visibly when launching from rest, and bars, either the bars (springs) have to flex, or the axle housing has to wheel hop can occur in braking, especially when running without the twist, for the suspension to move in roll. This is important because the weight of a trailer. There is also a lot of torque roll under power.

To be continued next month…

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48-49 REV30N11 Consultant-MPbsAC.indd 49 22/09/2020 21:14 TECHNOLOGY – SLIP ANGLE Of springs and dampers The meaning and usefulness of suspended mass natural frequency numbers

By CLAUDE ROUELLE

Race engineers and drivers work together to set up spring and damper settings to fi nd the desired compromise between tyre grip and wear as a function of the circuit surface characteristics and bumpiness

n the last article we stated that spring The second one is simply a determination spring that represents the eff ect the spring stiff ness choice is based on experience of the suspended mass natural (undamped) has at the liaison of the wheel with the and subjective appreciations, as frequency. The basic formula for this is ground. Wheel rate will be in series with the Imuch as it is on objective science. tyre rate (or tyre stiff ness if you prefer). The determination of the spring stiff ness The wheel rate, K, is the spring rate is dependent of the track macro (bumps, divided by the square of the motion ratio. kerbs, slope, banking) and micro (asphalt where, roughness) defi nitions, the track temperature, the car mass, inertia and aerodynamic properties, the tyre (in itself a dark science) K is the wheel rate expressed in N/m grip, wear and thermal characteristics, the M is the suspended mass expressed in kg eff ects that suspension stiff ness can have on f is the suspended mass frequency and is The motion ratio is the ratio between the car reliability and, fi nally, driver skill. expressed in cycles per second or Hertz (Hz) wheel movement and spring movement, as Most of these inputs are not easily Put simply, the wheel rate is a ‘virtual’ explained in more detail in the box below. qualifi able and quantifi able. However, there are two fundamental engineering tools that we can bring into our decision process. Some people have diffi culty understanding the reason for the use of the square of the motion ratio to calculate wheel rate from spring stiff ness. Here is a simple explanation. If you take the principle Shapes of things of conservation of energy you can write that The fi rst one is the defi nition of track bumpiness. What are the shapes of the track bumps and how often, and at what speed, That equation supposes there isn’t any friction in the rod ends and / or the bellcrank bearings. do the tyres hit these bumps? This will help These frictions always exist in practice but, for the simplifi cation of the demonstration, we will in the spring stiff ness choice. We will discuss consider them negligible. this further in a future article on a quarter car As the spring force is nothing other than the spring stiff ness * , the spring movement in the previous model simulation. That simulation tool allows equation can be re-written as us to defi ne spring and damper depending what the race engineer and driver are looking for, and the compromise they will accept Or between tyre grip and wear, ride height consistency and its eff ect on aerodynamic performance and expected response.

50 www.racecar-engineering.com NOVEMBER 2020

50-52 REV30N11 OptG-MP3acbsAC.indd 50 22/09/2020 21:19 For those still not convinced, Figure 1 ratio is applicable to the damper too, as when you double the spring stiffness, you shows a simple sketch extracted from the illustrated by the sketch in Figure 2. only increase frequency by 41 per cent, OptimumG Advanced Vehicle Dynamics because the square root of two is 1.41. seminar that will help full comprehension. • Do not forget that wheel rate is in series On the left, the real spring, and on the with the tyres (and possibly some badly right, the ‘virtual’ spring that represents wheel designed suspension compliance). rate. In this example, the motion ratio is two, Here are a few useful comments and Springs in series are always softer that is to say the wheel moves twice as much warnings to avoid often made mistakes: than their stiffer spring, and you do as the spring. If wheel movement is double • Spring stiffness is expressed in Newtons not double the whole suspension the spring movement, it is as if the ‘virtual’ per metre (N/m) not in Newtons per stiffness when you double the spring. spring (wheel rate) is half the spring stiffness. millimeter (N/mm). That is a classic error. When your car is not working However, as you can see, the force is also • Be aware this equation is for one and you suspect the suspension is half of the force on the spring. So, if we have corner of the car only. Third (heave) too stiff, or too soft, changing the twice the movement and half of the force, we springs are not taken into consideration spring stiffness by only five per cent have a wheel rate that is a quarter of the real here, nor are anti-roll bars. will not make a big difference. spring stiffness. As the motion ratio is two, • Look at the main formula and keep • Motion ratio is the ratio between wheel the wheel rate is the spring rate / 22. Hence things in practical perspective. Because movement and spring movement, not the use of the square of the motion ratio. the natural spring stiffness is a function the other way around. We must be careful Note that the notion of the motion of the square root of the spring stiffness, here as some engineers in specific racing series (NASCAR especially) often express Figure 1: Motion ratio between wheel rate and spring rate motion ratio as spring movement vs wheel movement. That is not right or wrong, we just need to make sure everybody uses the same definitions in their calculations. Be careful, though, because 1.12 = 1.21. An error of 10 per cent on the motion ratio (because of non-respect of suspension parts manufacturing tolerance, for example) is an error of 21 per cent on wheel rate. • On a suspension such as McPherson, motion ratio will always be bigger than one, and the wheel will always be moving more than the spring. • On a car with a push or pull rod and rocker (some call it a bellcrank) suspension, spring movement can be bigger that wheel movement. The motion ratio in this case will be less than one. • In most racing suspensions, the spring and damper are assembled in one unit, often called a coilover. The NASCAR front suspension, where spring and damper Figure 2: Motion ratio between wheel rate and damper rate are not on the same axis, is an exception. • A motion ratio smaller than one (where the spring and damper move more than the wheel) will generate more spring and damper movement than the wheel, and therefore more spring and damper speed and acceleration. For a given wheel up and down movement at a given frequency, we will get the same frequency at the spring and the damper (again, supposing compliance and friction of the rod ends and rocker bearings are negligible).The same frequency but a longer stroke results in higher damper speed and acceleration, whereas with higher damper speed we have more resolution and adjustability. To use a very basic example, it will be easier to control wheel movement with a damper that has a speed in a -250 to +250mm/sec window than one with a -50 to +50mm/sec window.

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50-52 REV30N11 OptG-MP3acbsAC.indd 51 22/09/2020 21:19 TECHNOLOGY – SLIP ANGLE

The advantage of the suspended mass natural frequency is it links both masses, kinematics of the motion ratio and suspension stiffness

• At the other end, bigger speed and Spring stiffnesses themselves are rarely or 118.5N/mm, or 675lbs/in for our bigger speed changes (accelerations) constant. If you put a spring on a spring old fashion American friends. create the risk of damper cavitation. tester, measure the stroke and the force, The experience has shown that Risk of cavitation in a damper can be and make a graph of force vs movement natural suspended mass frequencies (also decreased with higher gas pressure, you will rarely get a straight line. Without called undamped frequencies) are in the but at the cost of higher friction. going into the details of the spring stiffness following regions: for passenger cars – • As damper force (N) = damping rate (N/ equation, we will simply remind you that 1.1Hz (very soft) to 1.8Hz (very stiff); for (mm/sec)) * damper speed (mm/sec), the when the spring is compressed, there will non-aerodynamic racecars – 1.5-3.0Hz, and same damping force can be achieved with be more and more contiguous coils and for aerodynamic racecars – 3.0-7.0Hz. less damping rate and more damping the spring stiffness increases when the Yes, 7Hz seems particularly high, but let’s speed (that is achieved with a small number of active coils decreases. From not forget this kind of situation occurs on motion ratio) than with more damping this point of view, torsion bars offer a more front suspension of aerodynamic racecars rate and less damping speed (that is constant stiffness than a regular spring. for which front ride height control is critical, achieved with a high motion ratio). and such cars are often seen with an • For a given wheel movement and given Practical constraints additional third (heave) spring, and most wheel force, a small motion ratio will At the end of the day, besides the equations probably the use of bump stops, too. result in a longer and softer spring developed here, the choice of motion ratio is What’s important to note is that each and a longer and softer damper, but most often dictated by practical weight and car mass and suspension are different. Each keep in mind the implications damper packaging constraints, and the answer to this track or rally special stage is different. How and spring sizes and characteristics simple question: do you design a coilover then do we compare the suspension stiffness will have on weight and packaging. unit and decide its dimensions and of a heavy racecar with a light rally car? The Small motion ratios seem appealing characteristics to adapt it to a given existing advantage of the suspended mass natural for their higher speeds and window suspension, or do you design a suspension frequency is it links both masses, kinematics of adjustments, but impose serious around a given damper? of the motion ratio and suspension stiffness, restrictions on the car designer in terms In other words, a Formula 1 car designer so it is a common denominator that allows of packaging. Weight and packaging imposing damper and spring sizes and us to compare car suspension stiffness. are always bigger challenges in cars characteristics to a subcontractor is a very But how stiff is too stiff? How soft like Formula 1 than, say, Baja cars. different story to a Formula Student team is too soft? Now we are back to the • Motion ratio, MR, is not necessarily – in that was given a free set of dampers via intuitive and experimental approach fact rarely – a constant number. By design some sponsorship, and has to design its car’s describe in our previous article. At least, and / or because of compliance, it is suspensions around the imposed dampers. the suspended mass natural frequency often a function more than a number. Taking the following equations together, is giving us the beginning of a reference • In fact, a non-linear motion ratio could point on the map of development. have some advantage, especially for cars Or what we call a ‘magic number’. with aerodynamic ground effect. With So, when your car works well, be sure to these, we want a relatively soft suspension note the front and rear natural frequency. at low speed to get maximum tyre grip Then, the day you are lost, at least you (we have explained in previous articles can go back to this reference. how the tyre ‘hates’ vertical load variation) and a stiff suspension at high speed to Slip Angle is a summary of Claude Rouelle’s maintain a low ride height, despite the OptimumG seminars, which are held worldwide downforce that is square of the speed throughout the year. The Data Driven Performance sensitive. There are three ways to achieve Engineering seminar presents a number of data this compromise, and they can be used we can define the spring stiffness for a acquisition and analysis techniques that can be used by separately or together: variable spring rate given frequency and a given motion ratio. engineers when making decisions on how to improve (achieved with changing the spring pitch, vehicle performance. wire diameter and spring outside diameter Ks=4 π2 f 2 M MR 2 OptimumG engineers can also be found around the along its length), variable motion ratio world working as consultants for top level teams. and bump stops (made of polyurethane Where Ks is the spring stiffness (N/m), M Check out our seminar calendar on the website: optimumg.com/calendar or even assemblies of Belleville washers). the suspended mass (kg), f the suspended For example, if motion ratio is 0.9 at mass natural frequency (Hz) and MR high ride height (low speed) and 0.8 at the motion ratio (non-dimensional). CONTACT low ride height (high speed) with a spring For example, let’s consider a car’s left front Claude Rouelle constant stiffness of 400N/mm, wheel corner mass (measured on scales) that is Phone: + 1 303 752 1562 Enquiries: [email protected] rate will vary from 400 / 0.92, which is 250kg, with a non-suspended mass of 42kg. Website: www.optimumg.com 494N/mm to 400 / 0.82, which in turn The suspended mass will therefore be 208kg. is 625N/mm. That is a 25.6 per cent If the motion ratio is 0.95 and the targeted wheel raising rate. Not negligible, natural frequency is 4Hz, the spring will be and not something to be ignored. Ks=4 π2 4 2 208 0.95 2 = 118,545N/m

52 www.racecar-engineering.com NOVEMBER 2020

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53_1120_RCE.indd 53 22/09/2020 16:58 TECHNOLOGY – GRAPHENE NANOFLUIDS Fluid dynamic Graphene was discovered in 2003 and hailed a ‘miracle’ material. Now it is showing another string to its bow in nanofl uid cooling technology By GEMMA HATTON

54 www.racecar-engineering.com NOVEMBER 2020

54-64 REV30N11 Graphene-MP2AC.indd 54 22/09/2020 21:03 This type of cooling technology could revolutionise the way our racecars and road cars look

NOVEMBER 2020 www.racecar-engineering.com 55

54-64 REV30N11 Graphene-MP2AC.indd 55 22/09/2020 21:03 TECHNOLOGY – GRAPHENE NANOFLUIDS

raphene is a single layer of carbon atoms, or graphite, By suspending graphene in solutions, it is possible to dramatically enhance the liquid’s thermal properties tightly bound in a hexagonal Ghoneycomb lattice structure. At one atom thick, graphene is the thinnest material on Earth. It takes three million sheets of graphene stacked on top of each other to achieve the thickness of a human hair. Its perfect crystalline structure and strong interatomic bonds also make it the strongest material on the planet, boasting strengths 200 times that of steel. Despite this, it’s also the lightest material, with one square metre of paper weighing 1000 times more than the same size piece of graphene. Not enough? It’s also an excellent conductor of electricity, and of heat at room temperature. Perhaps now you can start to appreciate why there is such a hype surrounding graphene, and why it has the potential to revolutionise many industries. In the motorsport and automotive sectors, graphene has mostly been utilised in nanocomposites, enhancing resin systems through nanoplatelet reinforcement. This is where graphene is mixed into resins, which are then combined and cured with layers of carbon fibre, greatly increasing the inter- laminar bond strength and, consequently, shear toughness. The likes of McLaren and other F1 teams have experimented with graphene in composites, but it is currently banned under the technical regulations, along with carbon nanotubes. The closest graphene composites have advanced cooling applications. Many systems come to motorsport so far has been the BAC have been conceptualised based on the It works about 60 per Mono (RE V28N8), which made BAC the first limitations of the fluid, so changes are made manufacturer to develop a car incorporating elsewhere within the cooling system. We’ve cent more efficiently than graphene technology. Graphene-enhanced been able to help re-focus the whole industry carbon fibre composite panels were used on understanding how we can incorporate traditional cooling fluids for the rear wheelarches, which not only these new liquids, and what that means not improved the stiffness of the chassis but also just for performance, but also the design of Shannon Notley, founder of Flexegraph reduced weight by 20 per cent. cooling systems in general.’ Notley spent a large chunk of his career at Fluid technology the Australian National University, where he Interestingly, however, it’s not just composites researched and developed the technology when Professor Sir Andre Geim and Professor that can benefit from graphene’s phenomenal to suspend high quality graphene particles Sir Kostya Novoselov at the University of properties. Researchers are currently in liquids for large scale production. Like Manchester in the UK found a way to isolate developing methods to coat tyres with layers everyone else, he initially thought developing it in its pure form in 2003 that it became of graphene to reduce rolling resistance and graphene for composite reinforcement would a material that could be worked with. improve grip. While the material’s sensitivity be the way to go but, with the market already Suspending it homogenously within a liquid and electrical conductivity, along with its crowded, he opted for nanofluids instead. is even more of a challenge. thin structure, makes it perfect for sensors ‘We thought, well, we need to get to ‘It’s not an easy thing to do,’ confirms and other electronic components. What you market as quickly as possible, what is the Notley. ‘Broadly speaking, you have two main probably haven’t heard of, though, is how easiest product that we can produce? categories of material: hydrophilic, which love graphene can also be utilised in nanofluids. Because we were already producing to be in water, or hydrophobic, which hate ‘Graphene has the highest known thermal graphene in water, that’s basically 95 per cent being in water and prefer to be in oils. The conductivity of any material, which is about of the way to a cooling liquid already. It was unique properties of graphene mean it sits 10,000 times that of a base fluid such as pretty much ready to go,’ says Notley. right on the border of those two categories. water,’ explains Shannon Notley, founder of So it doesn’t really like water and it doesn’t Flexegraph. ‘So by putting small amounts of Suspension challenge really like oil either. Therefore, you have to graphene into these liquids, you can enhance Although this sounds simple, graphene tune its properties to get it to be stable within the thermal properties quite substantially. is not the easiest material to work with, those different liquids, which is not trivial.’ ‘It works about 60 per cent more especially when trying to suspend it in liquids. To help achieve the stable suspension efficiently than traditional cooling fluids, and Historically, graphene was predicted to be of graphene particles within water, as well that opens up a big range of opportunities for too unstable to be produced. It was only as tune the specific properties of a coolant,

56 www.racecar-engineering.com NOVEMBER 2020

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57_1120_RCE.indd 57 22/09/2020 15:57 TECHNOLOGY – GRAPHENE NANOFLUIDS

up to 20 other ingredients can be added to the liquid. ‘Each has its own use case to try Road car coolants have to operate in environments ranging from -35degC to 110degC, and for 50-80,000km intervals and improve the performance of the liquid,’ explains Notley. ‘There will be anti-corrosion additives, anti-microbials, dispersants as well as dyes. You add in all of these components to improve performance, but they can either have a positive or negative eff ect on stability. ‘One of the things we’ve been working on in particular over the last six years has been how do we make the suspension of particles stable within complex mixtures, whilst coping with the temperature cycling of a traditional internal combustion application over many years for road car applications.’ Technical challenge Although F1 engines demand a lot from the coolant, because the engine operates in relatively consistent environmental temperatures, this is actually much easier to achieve higher heat rejection will improve failure. The ability to reduce or re-use heat design for. Whereas road car engines have to the overall thermodynamic effi ciency of the more effi ciently across the whole system, perform in conditions ranging from -35degC engine, and consequently fuel effi ciency. rather than just a specifi c area, due to to 110degC. Add to this the lifespan of an F1 ‘Most modern engines are already very improved thermal conductivity is important.’ coolant, which is one race, compared to 50- close to the knock limit but, if you can run Maximising heat rejection doesn’t just 80,000kms for a road car and you can start to your engine hotter, even by a small amount, improve engine and fuel effi ciency, though, it appreciate the technical challenge. then the fuel effi ciency gains can be quite also improves the effi ciency of the radiators. Improving effi ciency is the major driver substantial,’ highlights Notley. ‘Then there is This means they require less airfl ow and can behind every aspect of racecar and road car the benefi t of evening out the temperature therefore be smaller and manoeuvred lower development today. Extracting the maximum across a system. For example, hot spots on down in the car, off ering attendant packaging performance out of the minimum amount cylinder liners can lead to a process called benefi ts. This in turn reduces drag and lowers of fuel, material or time is how motorsport nuclear boiling, where gas bubbles form the c of g, improving both aerodynamic can not only be more sustainable itself, but on the surface and the heat cannot be effi ciency and vehicle handling. also help other industries become more transferred through the gas effi ciently. These Despite decades of teams optimising sustainable, too. Therefore, coolants that can hot spots lead to fatigue and eventually the packaging of radiators, the thermal

One of the major challenges faced has been keeping a graphene solution stable in the temperature range experienced in an internal combustion engine. Surprisingly, this is less of an issue in motorsport than in road car technology

Coolants that can achieve higher heat rejection will improve the overall thermodynamic effi ciency of the engine

58 www.racecar-engineering.com NOVEMBER 2020

54-64 REV30N11 Graphene-MP2AC.indd 58 22/09/2020 21:03 AIR JACK SYSTEM

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591120_RCE.indd 59 22/09/2020 15:58 TECHNOLOGY – GRAPHENE NANOFLUIDS

A side effect of the improved thermal properties of graphene nanoliquids is a reduction in radiator and cooling system size, which is beneficial in motorsport but also far beyond

performance of coolants has always restricted anywhere now, so the car was completely the fundamental design philosophy behind packed. By being able to cool all the different The ongoing effects of cooling systems. But this is no longer the case internal combustion and hybrid systems, each with graphene nanofluids. Therefore, this type having very different temperature ranges, this can be far greater of cooling technology could revolutionise the with the one liquid, we were able to have way our racecars and road cars look. just one cooling loop. This is, of course, very than just temperature. attractive from a cost, manufacturing and Wasted energy packaging perspective.’ They can start to impact ‘One of the biggest things that often holds To demonstrate the magnitude of back performance is getting rid of wasted performance benefit of these graphene aerodynamics and weight energy in the form of heat,’ notes Marc nanofluids, Flexegraph has conducted a Priestley, director of motorsports and high- whole host of tests. One of which was a Marc Priestley, director of motorsports and performance engineering at Flexegraph. ‘So, if back-to-back comparison between an early you can do that in a much more efficient way, iteration of graphene nanofluid against a high-performance engineering at Flexegraph using the properties of graphene particles, conventional F1 engine coolant. the potential is huge. You can easily fast forward and think that this could start to Power boost direct or indirect cooling. The former uses change the design of power units, as well as ‘What the F1 team saw on their dyno testing fluids in direct contact with the electrical slim down radiators and bodywork. was a reduction in temperatures of around components. So, for batteries for example, the ‘The ongoing effects of this can be far two degrees,’ reveals Notley. ‘For them that fluid surrounds the individual cells, while for greater than just temperature. They can was quite substantial, because every 0.2degC motors the fluid flows around the windings. start to impact aerodynamics and weight. drop in temperature equated to about 10 For this, non-conductive dielectric fluids, It’s fascinating technology but the ongoing additional horsepower they could potentially which are typically oil-based, are used. potential of this, which we’re nowhere near get out of the engine. If you’re talking a full Indirect cooling, on the other hand, fully realising yet, is huge.’ two degrees, that could give a team a major utilises cold plates, which are essentially Another benefit in terms of packaging boost in potential engine performance, metallic heat sinks that have channels of is the reduced cooling infrastructure that a from a liquid that is relatively low cost to cooling fluid flowing through them. These more thermally efficient coolant enables. implement into a system.’ can be attached to the cells of the battery ‘One Hypercar manufacturer we’re Of course, modern racecars don’t just and the stator of the motor through thermal working with had an extremely complex have to manage the temperature of the adhesives. However, separating the coolant cooling system with eight separate cooling engine, but also batteries, motors and and the components with effectively a loops within the car,’ recalls Notley. ‘Modern inverters, too. Conventionally, these types of metallic layer induces thermal resistance vehicles don’t have much available real estate components are cooled in one of two ways: and therefore a loss.

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61_1120_RCE.indd 61 23/09/2020 15:07 TECHNOLOGY – GRAPHENE NANOFLUIDS

Hybrid and electric car technology requires further cooling loops for the batteries, inverters and electric motors. Graphene nanoliquids can not only help reduce temperature across the whole system but improve battery life, too

Modern rapid prototype techniques can generate cold plates with thin walls, allowing teams to achieve similar levels of heat rejection as direct cooling, but without the weight penalty of flooding a battery or motor with coolant. Reducing the temperature of the battery is vital for safety and performance. ‘You can think of an as a giant toaster passing current through a system, and there are losses in that system, which result in heat that needs to be dissipated,’ explains Notley. ‘The faster you charge or discharge a battery, or the bigger the battery, the more heat it will generate. If the battery experiences high temperatures for an extended period, the number of cycles you get out of it reduces quite substantially. ‘But there are other applications for our coolants, too. During fast accelerations, the battery discharges at a phenomenal rate, which then subjects the inverters to huge heat loads, so there are additional opportunities there as well.’ To keep the battery within its optimum temperature range, these coolants can also be used to warm the battery up. ‘For us, it’s all about rate. You’re either pulling heat out of a system more quickly or putting heat in more quickly,’ explains Notley. Improved cooling fluids do not change the amount of energy stored, but better heat transfer uses the energy more efficiently

62 www.racecar-engineering.com NOVEMBER 2020

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63_1120_RCE.indd 63 23/09/2020 17:53 TECHNOLOGY – GRAPHENE NANOFLUIDS

‘Our cooling fluid does not change the So essentially, the more graphene particles amount of energy the liquid can store, but it you disperse into a given fluid, the higher The more graphene changes the rate at which heat is transferred the viscosity levels, but also the greater across the system. So when you have a cold the thermal efficiency. particles you disperse start, you can bring the temperature of the ‘For example, each team’s pipework battery up quicker using our liquid.’ and channel sizes within the radiators are into a given fluid, the That helps to improve overall efficiency in slightly different and so the fluid needs a a battery-based system. bespoke formulation to suit that particular higher the viscosity system. We’re at some fairly advanced testing Performance tweaks with a couple of different teams now in levels, but the greater After successfully proving the benefits Formula 1 and IndyCar and we’ve been able graphene nanofluids can bring to both to utilise their amazing testing facilities to the thermal efficiency motorsport and automotive, Flexegraph is give us some really detailed results. now developing techniques to tweak the ‘Getting involved with motorsport has Marc Priestley performance characteristics of the fluid to suit boosted our development as much as it each team’s particular set-up. has helped teams get closer to a solution as ‘A lot of the work we’re doing now is well. It’s a really interesting space,’ concludes problem that graphene nanofluids can help finding the perfect viscosity and thermal Notley. ‘There has always been this idea that to solve. A lot of the engineers we work with efficiency level that works for each set- the properties of liquid cooling are static, say they’ve never heard of this technology up,’ says Priestley. ‘One of the big factors and there’s nothing better than what’s been before and initially don’t believe us. But everybody wants to be sure of is our fluid around for the last 100 years. But when then when they do the tests and see the won’t have a detrimental effect on viscosity. people realise we have a liquid that improves capabilities of our coolants, as well as the The way graphene works is to trade off heat transfer, minds are blown. Whenever benefits this brings to their systems, they viscosity for the heat thermal efficiency. we speak to someone new, we find another become believers.’

Other applications

ooling engines and hybrid components is not the only application of graphene nanofluids. C ‘We cut across three major industry verticals – automotive, computing and power generation,’ says Flexegraph’s Shannon Notley. ‘That demonstrates the breadth of this sort of technology.’ The company has already developed coolants that manage the temperatures within the charging infrastructure for hybrid and electric trucks and buses. By utilising the higher thermal conductivity of graphene, not only have the charging cables reduced dramatically in size and weight, but the charge time has also decreased, so vehicles can be back on the road quicker. Another application is computer cooling. Flexegraph’s liquid cooling technology is already being used to manage the thermal output of high- performance computers and large data centres. Interestingly, as well as the need to be kept cool, motorsport and computing share another requirement, the use of dyes. ‘There is only one colour you’ll get with graphene coolants, and that’s black. But, interestingly, a talking point for many customers has been the colour,’ reveals Graphene coolants are already in use in electric truck Notley. ‘They want the coolant to be bright yellow or and bus infrastructures, reducing cost and down time green so, if there’s a leak, it’s immediately visible and and therefore improving productivity the engineers can tell exactly what fluid has leaked and where it has come from. ‘Some of our PC cooling customers have also requested we change the colour for their high-spec Motorsport and gaming machines. Often these now have transparent computing share cases with liquid cooling loops around the CPUs. It’s essentially a hot rod for computers, and people want another requirement, to have brightly coloured dyes circulating around their consoles. It’s an interesting additional challenge we the use of dyes never thought we’d have to consider.’ ‘Hot rod’ cooling for your games console?

64 www.racecar-engineering.com NOVEMBER 2020

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65_1120_RCE.indd 65 23/09/2020 18:02 TECHNOLOGY – ADDITIVE MANUFACTURING

Powder keg

Additive manufacturing is a hot topic. Racecar looks at the pros and cons of the various current methods and their relevance to motorsport By LAWRENCE BUTCHER

66 www.racecar-engineering.com NOVEMBER 2020

66-73 REV30N11_Additive manufacturing-MP2BSAC.indd 66 22/09/2020 16:03 The big draw of AM is the ability to create geometries that would be impossible to achieve using subtractive machining or casting

dditive manufacturing (AM) technology has, over the past decade, established itself as Aalmost indispensable in the motorsport industry. As the mechanical properties of components produced using AM have advanced, so have the potential uses, and their adoption in applications where previously only machined or cast parts would be considered suitable. The scope of the technology can at times be bewildering, ranging from what one could term ‘hobbyist’ 3D printers through to industrial scale, multi-process machines capable of producing high-strength metal parts, fully heat treated and almost ready to fi t. As with any manufacturing technology, there are limits to what can and can’t be achieved, but these are constantly being eroded as machinery manufacturers’ process engineers advance their knowledge. This heat exchanger manufactured by Confl ux Technology is a perfect example of how the geometric freedom offered by AM can be exploited to optimise effi ciency

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F1 team, Alfa Romeo Sauber, has been using AM processes for over a decade now and has extended its technology partnership wth Additive Industries through to 2022

There is also an element of engineering The terminology of even just powder bed design theory having to play catch up with fusion methods can be confusing, with ‘brand There is an ever- new techniques. The entire concept of names’ representing what are effectively Design for AM (DfAM) needs to be adopted the same technologies. SLS (selective laser increasing range of to fully realise the benefits it can bring. The sintering) is generally used to refer to the ability to produce previously unmachinable manufacture of polymer parts, and direct metal types that can forms means engineers are having to re- metal laser sintering (DMLS) / direct metal think their design approaches, which have laser melting (DMLM) refers to, as the name be processed, covering been cemented over years of producing suggests, metal parts. parts within the constraints of traditional Polymer processes use lasers for material everything from gold to subtractive machining or casting processes. heating, while metals can be melted with In many ways, this shift is similar to that either lasers or electron beams. titanium and steel which occurred when five-axis machine tools became commonplace. Polymer processes Looking first at polymers, there are a Motorsport applications plethora of materials that can be deployed Meanwhile, its XT 2.0 material features carbon For the purposes of this article, we will in racing, with some larger outfits even now reinforcement and can be used as a substitute concentrate on the AM process most researching their own blends. Sauber, for for traditional carbon fibre composites in commonly employed for functional example, which has utilised SLS technology some applications. component production racing (see box out for over a decade, has developed a material on p71 for a description of the various current based on Nylon 12 that it employs for the Metal processes AM technologies), powder bed fusion, both production of parts such as brake and Moving to metals is where things get of polymers and metals. cooling ducts. Called HiPAC, it is reinforced really interesting, and it would be fair to with carbon fibres giving it a tensile strength say it’s where the most exciting current of 85MPa and, importantly, is temperature developments are taking place. There is stable up to 170degC. If one looks at the Alfa an ever-increasing range of metal types Polymer processes Romeo Sauber team’s pit lane equipment, it is that can be processed, covering everything easy to spot various adapters for leaf blowers from gold to titanium and steel. use lasers for used for brake and powertrain cooling For racing applications, the materials produced using this material. of greatest interest are aluminium and material heating, Another long time and prolific producer titanium alloys. With aluminium, most of polymer-based materials is Italian firm casting grades are available in powder while metals can CRP Technology, which offers a range of form, such as AlSi10Mg and AlSi12MG, reinforced powders. All falling under the though higher performance alloys have be melted with Windform brand, these are tailored for also come on the market. One such material specific demands. For example, its FX Black is Scalmalloy, developed by specialist AP either lasers or material is engineered to endure bending Works, which sees aluminium alloyed with and torsional loads, and exhibits good scandium and magnesium, giving finished electron beams impact resistance – similar to polypropylene. properties similar to 7075 wrought alloy.

68 www.racecar-engineering.com NOVEMBER 2020

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The AM components on this page made by French fi rm Polyshape, including a hydraulic block (below) and high-load parts such as the suspension upright (right and below right), show just how advanced additive manufacturing technology now is

Scalmalloy has an impressive tensile strength of 520 MPa (compared with AlSi10Mg, at 350MPa) which is about half that of Ti6Al4V titanium, but combines that with a density the same as AlSi10Mg (2.6g/cm3). In addition, its microstructure remains stable up to 250degC, making it suitable for high- Most notably, the Fraunhofer Institute For AM processes, the learning curve is still temperature applications. for Ceramic Technologies and Systems steep. Melting or sintering metals needs to When it comes to titanium, Ti6Al4V and (IKTS) in Germany has pioneered a process take place in an inert atmosphere. However, Ti6Al7Nb are the most commonly used that allows for up to four diff erent material some oxygen will always remain, which grades for AM and have been employed in a types to be mixed in a single part, with infl uences the properties of a fi nished part. variety of racing components, from roll hoop powdered metal or ceramic being deposited Additionally, much like casting, there will structures to suspension parts. Sauber, for in build layers simultaneously, along with a always be a degree of shrinkage or distortion example, has been working on functional thermoplastic binder material. to a part, either during manufacture or post- suspension rockers, while French fi rm Post-production, the parts are heated processing during such as heat treatment. Polyshape has produced suspension in an oven to sinter the materials together. uprights, including those used by Romain In this way the properties of parts can be Dumas in his Pikes Peak cars. precisely tailored, for example to maximise Another important AM-suitable metal thermal or electrical conductivity in certain There have been recent is Inconel, and a glance at any current areas, or enhance wear resistance (the process Formula 1 power unit will reveal exhaust can also deposit carbide). components produced in this material. Prior developments in the to the regulation clamp down on blown Process control exhaust systems, many teams used AM for the When it comes to creating reliable parts area of binder jetting production of tailpipes and other elements using AM, be they metal or polymer, to create geometrically complex forms that process control is everything. While this technology… to facilitate would be impossible to fabricate. is the case for any material manufacturing There have also been recent process, legacy technologies have decades, the mixing of different developments in the area of binder jetting if not hundreds of years, of accumulated technology, rather than powder bed systems, knowledge behind them. Even then, material types within a to facilitate the mixing of diff erent material porous or poorly consolidated castings types within a single AM part. are not uncommon. single AM part

70 www.racecar-engineering.com NOVEMBER 2020

66-73 REV30N11_Additive manufacturing-MP2BSACBS.indd 70 23/09/2020 11:12 Where complex parts with overhangs or hollows are This bewildering array required, such as this exhaust manifold of variables makes produced on a Renishaw AM machine, support structures correct characterisation are created as part of the Design for AM process and and validation of both machined off post-production materials and processes vital for reliability

AM front wing elements and other components made by the technical partnership between EOS and Williams F1

AM technology categories

ccording to the American Society for Testing and Materials (ASTM), through a heated nozzle and deposited on a print bed layer by layer, with there are seven distinct categories of additive manufacturing the build platform moving down to allow each new layer to be formed. Aprocesses. Not all of these are relevant to motorsport applications, The fi lament is almost always polymer-based, but the latest developments but it is wise to at least acknowledge their existence. include fi bre or metal-reinforced materials, as well as those with rubber- like properties. Vat photopolymerization Though having found the limelight as hobby machines, FDM has great This process uses a vat of photopolymer resin, which is cured in layers potential, particularly for producing prototype parts or even lightly loaded using UV light to form a net shape. This was one of the fi rst technologies functional components. utilised in motorsport, with teams using SLA (Stereolithography) to produce wind tunnel parts. Most teams still use such machines as they are Powder bed fusion capable of producing detailed parts, relatively quickly, sometimes with This category covers a host of diff erent methods of additive useful properties such as translucence. manufacturing, all of which rely on the heating or melting of a powder material stock. The material can be polymer-based or metal and it’s Material jetting probably the area with the most ongoing development. Not least in the Much like an inkjet printer, material is deposited layer by layer either as a production of metal parts with suffi cient properties to be used in highly jet, or in droplet form. Each build layer is then cured using UV light. One loaded applications. benefi t of this technique is that it can be used to produce multi-coloured parts, which can be useful for prototyping applications. Sheet lamination Quite a specialist process this one that relies on the ultrasonic welding Binder jetting together of thin sheets of material. This method involves two materials, normally a powder base and a liquid binder, with the binder deposited on the powder layer by layer to form an Directed energy deposition object. Not as commonly used, particularly in the motorsport industry, but Finally, another specialist process, but one which does have a role to play, current developments in this technology may make it more relevant. for example, in the restoration of historic motorsport components. An energy source, such as a laser or electron beam, is used to melt material Material extrusion that is either jetted (in powder form) or fed as a wire onto an existing Probably the most well-known form of additive manufacturing. surface. One of the most common uses of this process is the repair Commonly referred to as Fused Deposition Modelling (though this is a of shafts, and it can be a cost-eff ective means of reviving high value trademark of manufacturer, Stratasys), a fi lament of material is drawn components that are subject to wear or damage.

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There are also a host of other process which allows for inspection of internal dealing with a powdered bed of material, parameters that affect the final part: the structures at a microscopic level, even down large overhangs cannot be produced without power of the laser; scan speed; powder to being able to assess the microstructure of either compromising on surface finish or, in distribution; individual particle size; layer the metal at different points within a part. extreme cases, part integrity. Simply changing thickness, to name just a few. the way a part is orientated in the build This bewildering array of variables makes Design for AM chamber can remove the need for overhangs. correct characterisation and validation Extracting the potential of AM starts well Imagine the letter ‘o’ being printed, if done of both materials and processes vital for before any material processing takes place vertically, there are large overhangs, if printed reliability. If one adds in the potential and relies on the manufacturing process flat on the bed, there are none. for hidden internal features, which add being considered from the very start of the In some cases, overhanging features are further complexity to post-production part design process, the aforementioned DfAM. unavoidable, in which case support structures inspection, the challenge of validating the One example of the way AM changes are employed. These are additional printed performance of AM parts becomes clear. the very philosophy of design is the lack sections that will be removed via machining Take, for example, the development of of consideration needed for tool access or (or, in some polymer-based processes, can AM heat exchangers, which are currently part fixturing, which is ever present when be dissolved away) that support overhangs. being deployed by some Formula 1 teams conceiving parts to be machined. However, To reduce part production time, both during (see opening image in this feature). The there are a host of new factors that must printing and post-processing, and to optimise benefits these bring, both for packaging and be considered. Key amongst these are the material usage, it is desirable to keep their efficiency, are considerable. Not only can they potential for residual stress build up in use to a minimum. To this end, most software be constructed in any form, meaning they can parts, a part’s orientation within the build with dedicated Design for AM functionality be packaged in places traditional exchangers chamber, any support structures needed and will have the ability to automatically generate cannot, they are more efficient thanks to optimisation of a part’s topology. support structures in the CAD data, with the ability to precisely control the internal Addressing residual stress first, this is a various parameters that can be varied to wall geometry of the passageways, in order result of the rapid heating and cooling of a optimise their placement. to influence factors such as turbulence and part as the material is melted. If stresses get boundary layer formation. too high, or are concentrated in one area, However, their very effectiveness relies problems such as warping starts to rear its on extremely thin wall thicknesses, at the head. Various steps can be taken in the design Extracting the potential limits of the resolution available from the process to reduce the chances of distortion: highest-end AM machines. Any porosity avoiding large continuous surfaces, where of AM starts well before is clearly unacceptable. Ensuring these material is melted in an uninterrupted line, stringent demands are met requires an in- and the addition of a substantial base plate any material processing depth understanding of every stage of the that can be machined off post-production manufacturing process, and the effect any help keep part integrity. Additionally, the takes place and relies variations have on the material structure. pattern the laser traces over the powder can Validating whether these demands be from layer to layer, for example on the manufacturing are being met involves the use of both using a cross hatch system, to help even out destructive and non-destructive inspection stresses within a part. process being considered methods. Parts will be checked using x-ray The orientation of a part and the need micro-computed tomography (microCT), for support structures are interlinked. When from the very start

CAD file showing how a part is optimised prior to manufacture by AM, particularly in regard to stress build up during construction. Image courtesy Altair

72 www.racecar-engineering.com NOVEMBER 2020

66-73 REV30N11_Additive manufacturing-MP2BSAC.indd 72 22/09/2020 16:04 There is also research Proof positive of how far additive manufacturing has come, underway into AM Porsche is currently testing AM pistons made by Mahle processes that can incorporate electrical circuits into parts, opening up a host of possibilities for integrated functionality

Careful consideration of a parts features on a variety of input constraints. Instead of take much longer to manufacture than a can also reduce the need for support an engineer coming up with an initial design that is slightly less optimal from a structures. For example, if a hole doesn’t need concept for a part, and then refining it to functional perspective, but can be made in to be round, other geometries can be used ensure it meets the required load cases, half the time. Naturally, there is a catch. Such that are better at self-supporting, such as mass targets etc, with a generative design, systems are still in their genesis and a degree teardrops or diamonds. one moves back a step, simply providing of engineering caution still needs to be the software with the key constraints. applied to the results they generate. Optimisation In the case of a suspension upright, for Generative design incorporates TO, Beyond the design constraints around example, these constraints might include which is where software simulation is able to manufacturability, the big draw of AM is the wishbone and brake mountings, the pare down the design of a part to the point the ability to create geometries that would load cases, safety factors, material (or range where it retains only the material needed be impossible to achieve using subtractive of materials) selection, stiffness and available to fulfil its function. The result being the machining or casting. This capability opens manufacturing techniques. The generative very organic structures that are increasingly the door to a very high level of topological design program will then take all these commonplace on racing components (AP optimisation (TO) of parts, a process that constraints and output a variety of different Racing’s RadiCal brake calipers were one of predates AM but complements it well. designs, from which the engineer can choose the first mainstream manifestations of this TO is actually a subset of an approach a preferred option. approach). In the past, some of the more known as generative design, whereby a One solution might provide the ultimate far-out geometries that TO produce simply design, or number of design options, is in stiffness-to-weight ratio, but with a lower could not be machined, but AM makes them outputted by dedicated software, based safety factor than might be ideal, or it may possible. However, the aforementioned constraints of the AM process still need to be taken into consideration. Future potential The capabilities of AM continue to advance at a considerable rate, thanks to both improvements in machinery and engineering understanding of materials and processes. One only need look at projects such as Mahle’s production of AM pistons, currently undergoing testing with Porsche (it is also rumoured that F1 engine manufacturers have been experimenting within printed pistons). Such an application would have seemed impossible just a few years ago. Elsewhere, there is also research underway into AM processes that can incorporate electrical circuits into parts, opening up a host of possibilities for integrated functionality within components. Ultimately, the true potential of Additive Manufacturing is only just becoming apparent, and its use will surely only increase as understanding of its benefits Research into AM capability continues apace, with new materials, processes and machinery undergoing constant testing grows, and cost are reduced.

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66-73 REV30N11_Additive manufacturing-MP2BSAC.indd 73 22/09/2020 16:04 TECHNOLOGY – CHASSIS SIMULATION The art of knowledge

Or how to ask the right questions in racecar engineering

By DANNY NOWLAN

Firstly, you must get to know your racecar, backwards, forwards and side to side. This is where simulation helps, as the process forces you to understand how your car behaves ne of the biggest bugbears day. Teach him how to fish and you feed To understand a car – and I have with motorsport him for a lifetime.’ In other words, once you engineering is when people ask know the underlying principles, once you then in order to ask the Owhat is the optimum camber know how something genuinely works, setting? Or what is the magic ride height everything else comes out in the wash relationship through a corner? Or is there and questions such as those I listed at the right questions – it all boils a single metric to use for the lateral load beginning are a by-product. transfer distribution through a corner? In the motorsport engineering sense, down to tyres, suspension To me, these questions not just miss in order to ask appropriate questions, you the point, but also illustrate motor racing’s must know your car backwards. For me, this geometry and aero perpetual, and destructive, obsession with is the pay-off from using simulation. It’s not quick solutions. In recent years, this has the simulated data at the end, it’s not the been further amplified with engineering fact we changed this spring or that damper In a race engineering sense, from these education moving away from first principles and achieved a certain result. The benefit three things everything else flows. and seemingly becoming more interested is that if you are using something like in breeding a generation of computer-aided ChassisSim, the very process of simulation Tyres first engineering jockeys. forces you to understand your car. So let’s first talk tyres because, to quote The key to answering these questions It’s something I find myself very torn on. the late and great , the is to know how to ask the right question in About 80-90 per cent of the motorsport four contact patches of the tyres is what the first place. This is what we are going to engineering fraternity either can’t do this, separates you from St. Peter. be exploring in this article. or don’t want to do it, or think it’s beyond In order to understand the tyre, it Make no mistake, the art of asking the them. To that portion of the population I boils down to three graphs. The first is the right question doesn’t just form the basis say, trust me, it’s worth it. Traction Circle (TC) radius vs vertical tyre of sound motorsport engineering, but is To understand a car – in order to ask the load. This is illustrated in Figure 1. a critical life lesson. There is an old saying, right questions – it all boils down to tyres, This represents the heart and soul of ‘Give a man a fish and you feed him for a suspension geometry and aero. racecar performance because everything

74 www.racecar-engineering.com NOVEMBER 2020

74-78 REV30N11 Danny-MP2AC.indd 74 22/09/2020 21:07 flows downstream from this. Without a Figure 1: Traction Circle radius vs tyre load shadow of a doubt, the most significant aspect of it is the delta between the maximum tyre load seen on track and the load at which the tyre produces its peak TC radius. The bigger the delta between them is a direct measure of how stiff you run the car. For example, if that delta is under 50 per cent, this tells you to run stiff springs / dampers and low roll centres because you need to work the tyre. If it’s 20-30 per cent, this dictates high roll centres and soft springs because you need to look after the tyre. A trap for young players here is that most tyre test rigs will over predict the TC radius load peak. You get this model from actual data and the techniques for this I have spoken at length about before. Also, a quick note about thermal effects and the TC radius vs load characteristic. To ignore thermal effects on this relationship is a bit like ignoring gravity. You can’t. That being said, something like this with an Excel Figure 2: Normalised slip curve force balance sheet can get you into the ballpark very quickly. The other big driver of this will be the internal and surface temperature of the tyre. As a rough percentage, it’s about 60 per cent internal, 40 per cent surface, but that is only a rough rule of thumb. Normalised force The next curve to understand is the normalised tyre force vs slip angle / slip ratio curve. What I mean by normalised force is tyre force divided by the maximum TC radius value. Plot this and you get a curve that looks like Figure 2. The impact this curve has on car handling is massive, and it all revolves around the peak slip angle, the slope of this curve and what it does when you exceed the maximum slip angle and go post-stall. The smaller the slip angle and the Figure 3: Tyre lateral camber sensitivity steeper the slope means the car will be very sensitive to steer input. In aerospace parlance, this is often termed control power. How this curve drops off post-stall tells you a lot about how forgiving (or not) the car is when it’s on the edge of its performance envelope. For example, if that drop off is, say, a force factor of 0.95, the car will be quite forgiving post-stall. I spoke about this at length in my article about quantifying Rally dynamics. Conversely, when you start dropping to a force factor of 0.8, you are dealing with something very unforgiving. The last piece of the puzzle is how tyre force varies with camber. A rough guide from some F3 class tyres validated from race data is shown in Figure 3. While camber sensitivity is not to be ignored, it’s the lowest order effect of what we have discussed. Note in Figure 3 the

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Figure 4: A plot of roll centre height and camber vs roll deflection

max variation is a force factor of 0.88, with a peak of 2.7 to three degrees of negative camber. Where camber variation makes its Where camber variation presence felt is when you have a big tyre. The first generation A1GP car was a classic case in point of this. makes its presence felt is So how do we tie this all together mathematically? As shown in Equation 1. when you have a big tyre

(1)

Here we have,

F y = axle lateral force (N) = normalised function of force vs slip angle

c a m b = normalised function of force vs camber

F m 1 = Traction Circle radius of the front left (N)

F m 2 = Traction Circle radius of the front right (N)

While this is a simplification, it will put you in the ballpark. So, for example, to answer the question on control power, you take the derivative of Equation 1 with regards to slip angle. The camber relationship and Figure

1 dictates the F m 1 and F m 2 terms. Suspension geometry The next step is to understand the suspension geometry of your car. The ins and outs of which I have discussed in my book, The Dynamics of the Race Car, and in previous RE articles. However, if you want to distil this down into a picture of just what you need to know, Figure 4 nails it. This tells you how the roll centre is varying. It also tells you what the camber is doing. All you then need to do is cross reference this with what we discussed in Figures 1 and 3 and it starts to fill in the blanks. You perform the same analysis for pitch centre as well, albeit looking at movement in pitch. Secondly, you must understand the suspension geometry of your racecar. There is no one-size-fits-all for this

76 www.racecar-engineering.com NOVEMBER 2020

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Once you know Figure 5: CLA aeromap of front vs rear ride height for the first generation your map it starts A1GP car to answer some key questions

The other thing to pay attention to is bump steer. If we cross reference back to Figure 2, this tells you exactly where you need to go with that. If the peak slip angle is very small, it tells you immediately to minimise this. If you are stuck with a production car and tyres that have low to moderate slip angles, you can combine the two to tell you what toes you need to be running at. This is why the detail matters, because it tells you where to go with the set-up, rather than guessing. Aerodynamics The last piece of the puzzle is aerodynamics. It continues to astound me on a daily basis why most practicing race This is why the detail matters, because it tells you and performance engineers don’t learn how to calculate this from race data. Information where to go with the set-up, rather than guessing like that presented in Figure 5 is critical to understanding racecar performance. Figure 6: Total lateral force vs lateral load transfer distribution The map shown was a critical piece that helped Team China punch well above its weight in the first generation A1GP car. Once you know what this map looks like, it starts to answer some key questions about ride height sensitivities, where you need to run them and what you have to be prepared to put up with. Why bother doing all this? Because once you know what the tyres, geometry and aero are doing, all those questions about where to set cambers, ride height and springs all pop out in the wash. Armed with this knowledge, you can now put together plots of lateral force and stability index vs lateral load transfer distribution, as illustrated in Figures 6 and 7. The whys and wherefores of this I have Figure 7: Stability index vs lateral load transfer explained in previous articles, but the end result is you are no longer guessing at a set- up, you have a firm understanding of where the numbers come from. In closing then, the key to racecar performance is asking the right questions. Remembering the fish saying at the beginning, next time you want to know what the optimum camber range is for a car, or what the perfect range of ride height is, or what spring you should be running, ask first what the tyres are doing, what does the suspension geometry look like and what is happening with the aero. Ask those questions and the answers to the other questions will take care of themselves.

78 www.racecar-engineering.com NOVEMBER 2020

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MIA full page advert - Racecar - 29.7.20.indd 1 29/07/2020 12:35:21 BUSINESS TALK – CHRIS AYLETT Good, but tough, times ahead A golden opportunity to promote the value of the motorsport industry

trange times everywhere, so don’t worry A variety of solutions – fuel cells, hydrogen, The UK government clearly recognises the if you feel confused, you’re not alone! synthetic or biofuels, and ever more efficient future value of Motorsport Valley to a newly S After six months of restricted access, battery power, will appear on track in the near independent UK from January next year. we’re just beginning to open up. Despite fears of a future. R&D spending by the automotive industry The outstanding efforts, speed and agility of second wave of the virus, we need to get business in these areas will be enormous, and motorsport Formula 1 teams and their suppliers to meet the moving again. Using MIA links, I talk with a wide will take a share as new series will be needed to engineering demands of the respirator challenge range of business people from motorsport and demonstrate these solutions. alerted the government to the wider value of our high-performance engineering around the world, Just as Formula E enjoyed success, so will industry. You can help your business and build and things are heading in the right direction. synthetic-fuelled GT, electric karting and on this important momentum by writing a short, Motorsport entertainment is moving forward hydrogen hybrids be on track soon. upbeat message to your MP explaining what due, in part, to leadership from you do in motorsport. They Formula 1, NASCAR and series need to hear how valuable it who’ve accepted there being no is for the UK to build on this live audience. This is welcome world-class strength, as we news for competitors, sponsors become independent and leave and suppliers, but without major Brexit behind us. commercial impact as yet. Your MP will want to be seen The return of live audiences to support ‘winners’, and so will and amateur motorsport will take pass your comments to the time, so much of the business appropriate minister. In a post- value of the 2020 commercial and Brexit Britain, the government sporting year will have slipped needs winning, innovative SMEs by. The best the supply chain can who export, and that defines our plan for is an early start to the motorsport sector. 2021 season later this year and early next, with reduced budgets. Bang the drum An independent UK will see Great show substantial investment funding We face a new paradigm in the from government, much of which business cycle of motorsport will be focused on automotive entertainment. Series and teams innovation and technology, our have found they can put on The future is not full-electric, says the MIA, but right now it is a main focus and series like Formula motorsport heritage. We must a great show using less track E, with its BMW i8 safety car, illustrate the close relationship between motorsport and production step up and bang the drum time, days away from home loudly to MPs and ministers and testing, thereby reducing many costs. TV By 2035, governments propose that only alike, reminding them we’ve been energy- audiences still enjoy the racing, and so will live fully-electric cars will be allowed for sale. The MIA efficiency specialists since racing started over fans. F1 demonstrates how they can reduce the does not accept this, and recently joined with the 100 years ago and motorsport is a unique, vital time to deliver a race spectacle at one track, and IMechE to tell the UK government so. We suggest part of UK automotive’s future. then again the following weekend. that in addition to aiming for fully-electric power, I suggest you take time to carefully analyse NASCAR is running exciting races on a shorter they would be wise to consider hybrid power. and understand which of your company’s visit programme to its tracks, again reducing As our knowledge increases of the political, capabilities are most competitive and profitable, travel, accommodation costs and track time. In social and technological difficulties ‘battery as well as your speed, agility and competitive 2021, expect other series to adopt these measures power’ faces, any of which could destabilise the success, of course. As you move into 2021, you as they don’t impact on the audience or sponsors. proposed timetable and solution, we encourage a will need to choose which government-funded In time, teams and competitors will benefit, too. more prudent view be taken by investigating and projects could bring you the best reward. It’s easy Investment in top-class engineering supplies will demonstrating other potential forms of power. to become a busy fool by simply ‘chasing free continue as the need to win, by spending on the This approach would prompt not only an exciting money’ but that’s a big mistake. best product to secure a winning formula, will period of R&D investment, but the battle between We’re always ready at www.the-mia.com to remain an essential part of the process. various energy-efficient solutions on racetracks answer any of your questions, so contact us any Good news for innovative, quick-to-react around the world would provide knowledge to time. We want all in our industry to succeed and suppliers will be significant new spending on automotive OEMs and attract public interest. grow their businesses, and we must all work energy-efficient motorsport as automotive moves You can read our response here https://the- together to get through the next six months to zero emission in 15 years’ time. mia.com/news/521284. Let us know your views. and enjoy the good times that are ahead.

We’ve been energy-efficiency specialists since racing started over 100 years ago

NOVEMBER 2020 www.racecar-engineering.com 81

81 REV30N11 Aylett-MPAC.indd 81 22/09/2020 20:38 BUMP STOP Passion fruit

PIT CREW Editor Reflections on Le Mans 2020 Andrew Cotton @RacecarEd Email [email protected] here were no fewer than 121 stewards’ decisions Missing were BMW and Corvette, due to the IMSA schedule Deputy editor Stewart Mitchell at this year’s Le Mans 24 Hours and the only brought on by the global pandemic, but GTE is now so @RacecarEngineer blessing was the FIA did not seek financial expensive that small manufacturers can’t even dream of Email [email protected] Chief sub editor recompense for every breach of regulations. entering cars, and therefore GTE-Am (GTE cars that are one Mike Pye T Time was added to pit stops or, in the case of the final year old) is also closed to them. Art editor Barbara Stanley one for the Inter Europol Competition team, a driver missed It was a shame spectators were unable to witness this Le Technical consultant his driving time by 33 minutes, which was converted into a Mans as it was the end of an era. The LMP1 hybrids are now Peter Wright nine-lap deletion of their race distance. gone, bringing an end (for now) to 1000bhp Prototypes Contributors Mike Blanchet, Lawrence Butcher, Teams that checked brake pad wear and accidentally that can blitz the lap records. Toyota wanted to go for it Leena Gade, Gemma Hatton, Wouter Melissen, Danny Nowlan, Mark Ortiz, touched the car during refuelling were investigated again, to better the 3m14s record set by Kamui Kobayashi, Scott Raymond, Claude Rouelle although there were no penatlies, the stewards perhaps but he abused track limits at one corner on his fastest run Photography James Moy realising their zeal had overcome the spirit of racing at on Friday, and so his 2017 record still stands. Managing director – sales Steve Ross Le Mans, but long gone are the days of the 24 hour race Gone, too, could be the LMP2 competition. The class will Tel +44 (0) 20 7349 3730 Email [email protected] through the trees being the Wild West. remain, but there was uncertainty about the driver grading Advertisement manager Lauren Mills Stories of cars that had been written off on Wednesday system. The teams voted against mandating a bronze driver Tel +44 (0) 20 7349 3796 Email [email protected] or Thursday night qualifying, and in each car but no confirmation of Circulation manager Daniel Webb arriving all straight and perfect in the result came at Le Mans. Tel +44 (0) 20 7349 3710 Email [email protected] time for morning warm up were Spanners, whole When I started going to Le Subscriptions and Marketing manager fairly regular. Others where drivers Mans in the 1990s, it was common Luke Chadwick Tel +44 (0) 20 7349 3700 had mysteriously found gallons of practice for rent-a-drivers to turn Email [email protected] fuel in the forest that lines much toolboxes even, up with a suitcase full of cash and Publisher Simon Temlett Managing director Paul Dobson of the circuit were commonplace. go from team to team to secure a Spanners, whole toolboxes even, could be found in seat. If this Bronze driver rule was Editorial and advertising Racecar Engineering, Chelsea Magazine Company, Jubilee House, 2 Jubilee Place, could be found in the pitch dark applied, that suitcase would be London, SW3 3TQ out in the trees, and so it was this the pitch dark out considerably lighter as each of the Tel +44 (0) 20 7349 3700 Fax +44 (0) 20 7349 3701 year when Gabriel Aubry’s battery teams would need such a driver. Subscriptions went flat in his Team Jota LMP2 car. All that aside, it was LMP2 and Tel: +44 (0)1858 438443 in the trees Email: [email protected] According to the stewards’ GTE-Am that dominated the grid Online: www.subscription.co.uk/chelsea/help Post: Racecar Engineering, Subscriptions report, ‘The car stopped on track, figures this year. Nearly 80 per cent Department, Sovereign Park, Lathkill St, the driver exited the car and ’phone called his team. of the entries, yet both categories are under threat. The new Market Harborough, Leicestershire, United Kingdom, LE16 9EF A member of the team met the driver and supplied a LMDh regulations, announced at Le Mans and covered in Did you know you can manage component, which the driver fitted to the car. The car was this issue, will give the opportunity for the very best of the your subscription online? then able to continue. LMP2 teams to go for the overall win at Le Mans. Indeed, it Oversee your print and digital subscriptions online today simply by signing up at ‘During the hearing, the team representative admitted could be that they all buy the cars and have a go. https://www.subscription.co.uk/chelsea/Solo/ to these facts. He also stated that the car would not have On one hand that would be fantastic. In the 1990s, those Stay up to date with the latest issues, update your personal details, and even renew your been able to continue without this fix.’ that bought the Courages, the Deboras and the Riley and subscription with just a click of a button. Indeed, the car was out anyway and had been leading Scotts knew they would need a minor miracle to win, but Subscription rates UK (12 issues) £89 the category. As one team member said, ‘It had to be done.’ they still wanted to be there, racing in the top class, hoping ROW (12 issues) £100 It is in the record books as ‘disqualified’. for some of that good old Le Mans magic. On the other, all [email protected] Back Issues It was refreshing to see the old ways had not gone of the current LMP2 chassis manufacturers are on board www.chelseamagazines.com/shop entirely, and that team managers are still willing to roll the for LMDh, and if Porsche and Ferrari step up to provide News distribution Seymour International Ltd, dice. But gone are the sacrificial cars on the original entry engines and aero kits, that threatens both GTE and LMP2 in 2 East Poultry Avenue, London EC1A 9PT list that don’t stand a chance of pulling together the money one fell swoop. But if they all stay in the field and go to the Tel +44 (0) 20 7429 4000 Fax +44 (0) 20 7429 4001 to race. We no longer see Swedish gangsters emerge from top class, while bringing on other GT cars to maintain the Email [email protected] the truck with helmets on and a slightly different shape and balance, that’s progress, I suppose. Printed by William Gibbons Printed in England personality, only to then qualify 30s faster than before (or The world moves forwards and we should enjoy this ISSN No 0961-1096 USPS No 007-969 indeed ever again) with nary an eyebrow raised. time as at this race, with these teams and cars, and in this Disappointingly, we also no longer have the wide hybrid decade, despite the zealous stewards, we really variety of machines, as business overtakes passion. Just never had it so good. eight car makers were on the grid this year – ORECA, Toyota, www.racecar-engineering.com ByKolles, Dallara, Ligier, Porsche, Ferrari and Aston Martin. ANDREW COTTON Editor

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• Racecar Engineering, incorporating Cars & Car Conversions and Rallysport, is published 12 times per annum and is available on subscription. Although due care has been taken to ensure that the content of this publication is accurate and up-to-date, the publisher can accept no liability for errors and omissions. Unless otherwise stated, this publication has not tested products or services that are described herein, and their inclusion does not imply any form of endorsement. By accepting advertisements in this publication, the publisher does not warrant their accuracy, nor accept responsibility for their contents. The publisher welcomes unsolicited manuscripts and illustrations but can accept no liability for their safe return. © 2020 Chelsea Magazine Company. All rights reserved. • Reproduction (in whole or in part) of any text, photograph or illustration contained in this publication without the written permission of the publisher is strictly prohibited. Racecar Engineering (USPS 007-969) is published 12 times per year by Chelsea Magazine Company in England.

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